USB webcams under Linux are a bit of a tricky business as manufacturers release them so frequently. So Model 1 might be Win only, Model 2 might work under Linux and then Model 3 might be back to Win only. In which case you might have to search for an older version than what is curently in the shops.
I have an older Creative Webcam which works just fine but I don't think any of the newer ones do. In case you can find it, the OV511 chipset appears to be the best supported but often it's impossible to figure out before buying what chipset a camera has. You could try looking
here as this list is quite extensive though I don't know how up-to-date it is.
The other thing to be aware of is that you may have to load the driver explicitly and you may also need to manage the bus bandwidth manually if you have more than one USB cam.
Phil