Depends on the size of the USB stick and how much RAM the PC has. I've heard it works best when they're about the same size, correct me if i'm wrong anyone
If you're talking about the spec in your sig, it wouldn't be worth it unless your HDD is archaic.
Yeah you're right. I realise its for low memory systems, I just heard a 1:1 ratio for RAM and USB was optimal. I could just be making things up though, it's been a very loooong day at work!
Back on topic though, it's not worth it unless youre running a low memory system on vista as snakedoctor said. Though I think anyone who bothers with Vista and less than 1GB of RAM is a bit crazy.