# I have two HD's on my PC. Can I put 7 on one and keep Vista on the other?
Yes, that's what I did with the beta and RC of Win 7. Just choose the Advanced install option and choose the drive to install to but back up your data, including Email and internet favorites/bookmarks and any other data that may be saved with the install folders or in you profile. Make sure you have all your serial install disks and serial numbers for programs
# Can I access any or all my programs that are on Vista with 7 on the other disc?
If you mean run them, no. You can still access the folders where they were installed and any data there but you will have to re-install any programs you want to use in 7 under 7 so be sure you have all your install disks and serial numbers for programs.
# Same question as above but concerning my files.
As long as you don't reformat anything your data should be accessable. I keep my data on a seperate HD than the OS/programs just in case I need to re-install the OS. Back up everything anyway. Better safe than sorry and you should always back up your data anyway.