Back when I first got my vtab after much trial and error I finally got ADB to work on my windows 7 machine and got my Vtab rooted. After the unfortunate .57 update it seems ADB no longers connects. My best solution would be a Linux driver that works.
I finally got ADB to work by using the root tterminal program available in Ubuntu and was able to use the apps2sd trick mentioned in another current thread!
Try "software data cable"
It's free on the app Market, I'm using with my vtab1008 & Samsung Dart.
My pc runs Win7 home premium, 64-bit and it can see the internal memory as well as the external SD cards.