Questions about installing on External HDD

Hello, and today I bought a new 500GB External Hard Drive. Its a Seagate 500GB External Desktop Drive. Now on this drive, I want to install 2 partitions. First for iDeneb, and the second for storage space for my other PC. How would I go about doing this? Would I damage my External Hard Drive software-wise? When I first got it, it had a setup you could use for Windows.

System Compatability:
-Windows Vista
-Windows XP
-USB Ports

NOTE: This is not the first time I have installed iDeneb on my PC. I recently installed Vista Home Premium on my default 120GB Internal HDD.

Bump, please reply.

Bump... once again..

ffs, can anyone help?

Go ahead ! No problem :)

Did you installed? it wont damage your HDD