Stixter,
I'm not 100% on this, but the USB 1.1 thing may not be so much of an issue as drivers and hardware. It may be more trouble though if you were trying to stream too many tracks,etc. I was surprised how many of the ones I looked at were not actually 2.0.
The drivers also seem to be a really big part of that latency thing. So much so that there's a third party driver specifically aimed at latency (
USB2Audio - the low latency experience). I've got a Lexicon Omega and an Edirol UA-25 here, but the times I've needed them, I've done hardware monitoring. Lexicon has made some massive jumps toward better latency on occasion, just by releasing a new driver build, so I know it's important.
Take Care