upgrading from within beta 2

Hi all,

I posted this message to the general group and thought I'd better post it
here as well.

First of all here's what I got:
AMD Athlon XP 2100
FIC AN19C Mainboard w/Onboard VIA AC97Sound chip [Vista has no probs here]
Dual-Boot Configuration WindowsXP Pro and Windows Vista - 512MB Ram
NVIDIA GeForce MX420 w/64MB ram
M-Audio Delta 66 Sound Card for M-Audio Omni I/O.

When I attempt to upgrade from Beta 2 to RC1 Setup fails saying that files
are corrupted and/or missing. Setup does not even make it to the first
reboot. It rolls itself back in a second or two and that's it. Back to
square one.
I downloaded the ISO from MS and it was fine. Burned it to a DVD and
verified that the data is good yet I get that error message. [Sorry, I
didn't write the error code down]

Any ideas or suggestions?

Joe