Same Issue
So, I have been having the same issue, I'm using the x64 version of 7 with:
Core 2 Quad Q8200
XFX nForce 680i LT mobo
4 GB Corsair XMS RAM
Sony DRU-842A ATA DVD-RW
(edit: EVGA GeForce 8600GT graphics card. Dual Monitor Setup)
Mirror's Edge will not install properly, nor will other games, including Lost Planet Colonies, and Farcry 2. I tried installing it right after installing Windows 7, I tried doing so after I installed the Vista x64 drivers for the chipset, audio etc. and I have also noticed that it has been having a hard time with compressed files of all types, including multipart .rar, and .cab files. I tried removing the reg key as in the instructions, but the cmd window would not allow it, so I went into regedit and removed it manually... I have also tried installing the files after turning off UAC, after switching the setup.exe file to XP compat mode, with administration rights, and in various combinations.
I'm about out of options, and I would greatly appreciate any help. thanks in advance.