dual boot xp and win7 on separate hard drives

i have xp home 32 bit as my OS now and i have another hard drive installed and ready to install win 7 64 bit on to. can i do this with xp running or should i disconnect the HD with xp on it, then when i start the computer it won't see any OS and then i could boot from the win7 dvd and do a clean installl and then re=connect the HD with xp on it. then when i start computer i should get the choice of which one to boot from or is this not the way to do it?? i want the OS's on separate HD's for now as i am sure that not everything that i want to run will work on the 64 bit win7 until i can afford to get all the programs i use to work on win7.

Virtually all the programs that run on XP should run on Windows 7 x64, maybe an exception of a few.

You can do the install as you stated. One option would just to change the boot drive in the BIOS, which I done in the past with Linux on one hard drive and Windows 7 on the other hard drive. I did this because I don't really like boot loader software that much, and it's really not that much more time consuming either.

so i still don't have a clear idea of how to install win7 on a separate hard drive without installing over XP. is there an option with the win7 install dvd that allows me to install on any drive that i want? i could assign a drive letter to the new drive and install win7 there if that is possible. but what i need to know is can i do this with XP running and not overwrite XP?