Although they are very common nowadays and they all seem to offer pretty much the same functionality, USB flash drives can actually differ in a number of ways. In this USB flash drive roundup, HotHardware take a close look at the features and performance of a 4GB OCZ Rally2, a 16GB OCZ Mega-Kart, a 1GB Kingston DataTraveler ReadyFlash, and an 8GB Corsair Voyager GT. Here's a taster:

Kingston's DataTraveler: Transfer rates aren't the only thing to think about when buying a USB flash drive. Each of the drives in our round-up offer something different. If you want a simple and inexpensive way to boost application startup performance in Windows Vista via ReadyBoost, we wouldn't hesitate to recommend the Kingston DataTraveler ReadyFlash drive (1GB is around $20, 2GB is about $27). Not all drives support ReadyBoost, so it makes sense to buy one that is specifically designed for that purpose.

OCZ's Rally2: If you are like most people and aren't hopping on the Windows Vista bandwagon just yet, then ReadyBoost support doesn't mean much to you. Speed, price and large capacity are probably more important to you. In that case, it's easy for us to recommend the 4GB OCZ Rally2, which can be had for as little as $52 according to our PriceGrabber price search engine. Four gigabytes is more than enough storage for most people. Plus, the Rally2's aluminum housing will help protect it for years to come, and it looks really cool. That lifetime warranty is a big plus as well.

OCZ's Mega-Kart: When it comes to large capacity in a small package, the 16GB OCZ Mega-Kart is an obvious option. If patience isn't one of your strong points, though, we recommend looking at other options besides the Mega-Kart. While we like the Mega-Kart's credit card-sized housing and large capacity, we were left wanting more when it came to its tranfer speed, especially considering that it costs almost $170 after $30 rebate at several online stores.

Corsair's Voyager GT: If you want one of the best all-around drives on the market, look towards the Corsair Voyager GT. Simply put, the 8GB Corsair Voyager GT is one of the best flash drives we've ever had the pleasure of using. It's blazingly fast, rugged, feature-rich, and offers a whopping 8GB of storage space. Often times, the larger flash drives are slower, but that is definitely not the case with the Voyager GT. It is by far the fastest drive in this round-up, and we recommend it wholeheartedly if you can live with its slightly plump, rugged housing. At around $95, it's not the cheapest 8GB flash drive, but you get what you pay for. We'd love to see Corsair release non-rugged flash drives that are this fast and perhaps even a bit less expensive.