I have been using the Presonus FP10 firewire interface for about two years now, across multiple platforms. First it was Windows Xp, then it was Vista, and now Windows 7 (which is my favorite of course 
) In windows XP I experienced audio dropouts, weird glitches where it would not turn on while keep the blue LED lit, etc. In Vista surprisingly it was slightly improved, but still when used as the system audio as well, many many errors occurred (sorry presonus not a very good track record so far) And now, W7.
First let me say – there are no Windows 7 drivers. You have to cheat, and use the Vista drivers set to WDM. Thats the only temporary fix. It does ok if you use Asio4all, and can still use ASIO in your productions, however it just does that; OK. Not great.
I’m not sure if this is a hardware error or software, and if software whether the FP10 or Windows itself (though I am inclined to believe it is the FP10 simply because the drivers weren’t even written for this OS and W7 so far has been extremely smooth) but I often experience a stereo drop-out; meaning sometimes the audio will switch to mono. Though I believe it’s actually just one channel of a stereo signal because the audio will play out of one speaker (the left), and only the left channel of that stereo signal. Anyway. That’s bad.
I should ALSO mention that I do use the fp10 as a double for my system audio. Not really a recommended practice but there you go, I’m cheap lol. It is for the most part successful except for the few audio dropouts / glitches I experience
PERFORMANCE
The preamp in this thing is beautiful, and is capable of truly high-quality performance. That’s all there really is to say – it is sweet. The trade off with this device is modern computing inconvenience for really good sound at a low price if you can stomach it. For the price, it’s really the best you could do 
-Spence