You'll get the most support from this community if you use a version of VL, particularly VL6 (either Light, Standard Gold, or the upcoming SOHO). As nightflier said, you're not getting much support on the Ubuntu forums right now and if you can't get wireless working it's likely you'll abandon using linux altogether. Before that happens, I think it would be worth your time to give VectorLinux a go. My personal recommendation would be VL 6 Standard Gold, but if your machine has older specs then VL 6 Light might be a better route. Regardless, either one should serve you well and you'll get the most support from this community.
Nightflier's link above for 'VL6.0 Light LIVE' should be: http://vectorlinux.osuosl.org/veclinux-6.0/iso-release/VL6.0-Light-LIVE-Final.iso
NOTE: This is a live version (i.e. runs from CD). I personally think that a regular installable version (Standard Gold or Light Final) would be a better choice.
Last, your usb wireless device will be tough to get working and I base this on the fact that nothing pops up in a search engine indicating that anyone has ever got this device working. It would be beneficial to determine the exact chipset of your device as this will help determine the appropriate path to follow. I've _read_ that it's a broadcom usb chipset which may be a bad start, but we should try to determine this definitively. If that's the case then on the b43 website it mentions that all broadcom usb chipsets should try the RNDIS driver. So I then looked at this page (http://www.jooz.net/rndis/
) and it indicates support for a couple other USRobotics usb wireless devices (5421, possibly 5420). The site does say this:
Basically, any wireless usb adapter using rndismp.sys and usb8023.sys drivers under windows (check your driver cd) might work with this driver.
It would be worth your time to check this out on your driver CD just to see if this is the case. This is a pretty vague path to start with but might be worth more investigation.