Our review unit of the HP ProBook 4310s features the following configuration:

• Intel Core 2 Duo T6570 Processor (2.1GHz, 2MB L2 cache, 800MHz FSB)
• Microsoft Genuine Windows Vista Business (with option for Windows XP downgrade)
• 13.3-inch LED-backlit anti-glare HD display (1366 x 768)
• Intel Graphics Media Accelerator 4500MHD
• 2GB DDR3 1333MHz RAM
• 320GB 7200RPM HDD
• LightScribe DVD+/-RW Optical Drive
• WiFi (802.11a/b/g/draft-n), Ethernet, Modem, and Bluetooth Connectivity
• 4-Cell 37WHr Battery
• Limited 1-year standard parts and labor warranty
• Dimensions: 8.97 x 12.79 x 1.07 inches
• Weight: 4.4lbs
• Price as configured: $779

Build and Design
The ProBook family is HP's attempt to meet the needs of small and medium businesses. In short, these laptops need to have a good balance of features and security at a low price. On the other hand, small and medium business notebooks tend to have a very basic build and design in order to help bring down the cost of production. The ProBook 4310s, like the rest of the ProBook line, looks similar to a HP EliteBook with the square, industrial-looking exterior and recessed keyboard area. The key areas of difference between the EliteBooks and the ProBooks are that the ProBooks feature a mostly plastic construction rather than magnesium alloy and aluminum used in the EliteBooks.

The plastics help lower the cost and weight of the notebook, and as a result the ProBook 4310s tips the scales at a modest 4.4 pounds as configured. Unfortunately, the use of thin and light plastics means the ProBook 4310s doesn't feel particularly durable in your hands. The base of the laptop flexes heavily under pressure, the palmrests likewise bow slightly if you press down with your wrists while typing, and the back of the screen lid is extremely prone to flex. The plastics used in the 4310s should hold up fine if the notebook is being used as an office desktop replacement, but the chassis might not survive multiple drops off a desk or the kind of abuse you expect from a mobile workforce. Since this 13-inch notebook was designed to be mobile, I think it's safe to say that HP should have used thicker plastics or magnesium alloy to give road warriors a more durable laptop. On the bright side, the keyboard is pretty firm and was a joy to use while typing long documents.

The outer shell of the screen casing, palmrest area, and the speaker grill located above the keyboard are offered in your choice of Merlot or glossy Noir (black). The Merlot paint looks surprisingly nice and helps differentiate the ProBook 4310s from the plethora of boring black and gray business notebooks. Unlike the glossy Noir finish, the Merlot finish isn't reflective ... which also helps this notebook look more professional. The laptop screen housing is a mixture of firm and flexible materials. The frame around the screen is solid enough to prevent me from twisting the screen too much when force is applied, and although the back of the lid is extremely flexible I wasn't able to create screen-wide ripples across the display when I pressed on the back of the screen (as we observed with the larger ProBook 4510s).

Despite the plastic construction, the 4310s features hard drive shock protection in the form of HP 3D DriveGuard which will help to protect your hard drive in the event the laptop gets dropped or violently bumped. HP also includes HP ProtectTools with drive encryption, Device Access Manager, HP Spare Key (a program that helps employees access their computer in case they forget their password), HP Disk Sanitizer, File Sanitizer, and McAfee Security Solution for those small businesses that need reliability and ease of use but don't have the resources of a dedicated IT department.

One of our primary criticisms about the larger ProBook 4510s and 4710s was the fact that it was too difficult to make upgrades to those notebooks. While most notebooks have a removable panel on the bottom of the notebook to access the RAM, hard drive, and wireless card, HP designed the ProBook 4510s and 4710s so that you have to remove 10 screws and the entire top half of the chassis (including separate speaker grill, keyboard, and touchpad area) in order to replace or upgrade components. Thankfully, HP engineers have been listening to that criticism and have added removable panels to the bottom of the 4310s. As you can see in the image below, a small IT department or small business owner won't have to work too hard if they just want to upgrade the RAM or replace a hard drive. Granted, many businesses will never upgrade their notebooks and will simply use them as-is until they are replaced ... but the complexity of upgrades and repairs is something to keep in mind.

Speaking of the complexity of making upgrades, it's also worth mentioning that buying a pre-configured model is really the only way to purchase the 4310s (or any ProBook) at a reasonable price. As stated earlier, this configuration of the ProBook 4310s is available for only $779 on the HP website. However, if you decide to order a custom configuration the price starts at $972 for a configuration with a smaller 160GB hard drive! That's a painfully overpriced premium to charge for custom orders.

Screen and Speakers
The ProBook 4310s comes equipped with a 13.3" anti-glare display with a 16:9 widescreen ratio. At 1366 x 768 pixels, this 720p high-definition display is perfectly usable and features good color and contrast. The LED-backlit panel offers excellent brightness and we typically left the brightness set to between 50% and 70% when using the notebook indoors. We know many people are concerned about the transition from 16:10 to 16:9 ratio screens (because this means less vertical resolution) but the difference between 1366 x 768 and 1280 x 800 is pretty minimal.

Horizontal viewing angles are pretty good and you only start to notice some color shift after you get 75 degrees off center. Vertical viewing angles are only average as the screen begins to wash out from above and colors begin to invert from below after about 45 degrees in either direction.

HP generally impresses our editorial staff with the quality of the speakers used in their notebooks. Unfortunately, this isn't the case with the ProBook line. The speakers in the 4310s are good enough for watching a webcast or hearing system sounds, but the built-in speakers sound tinny and lack a good range of highs, middles, and lows. The highest volume settings are loud enough to fill an office with sound for a presentation, but the audio sounds distorted at the higher volumes.

Despite the weak performance of the built-in speakers, they are well placed above the keyboard to direct sound up and toward the user.

The headphone jack on the 4310s works well with the two different brands of earphones I used during the test. No static or other noise was noticed through the jack besides imperfections in the audio source itself.