VIA does not have USB drivers for any operating system later than Win 98. This is because of an agreement between VIA and Microsoft. Go to Windows Update and see if it can find the drivers for you.
And, as long as you have downloaded this Windows 7 from Microsoft, you can file a "bug report" with MS about the problem. I presume this is Win 7 RC 7100? Chris.
1)GA990XA-UD3, Phenom II 970 ,8Gb DDR3 1866, EVGA GTX560Ti,500Gb SATA II , LG DVD, Win 7 Ultimate 64bit
2)AX78, Phenom 9600, 9800GTX, XP Pro SP3