Yep, it's pretty simple. If you have a second hardrive as you say - just pop in your Windows install CD, and once you enter setup, select the second hard drive as the install location. After the install, you will get a screen to select the different OS'es at startup.
If you want to change the name of each OS in the startup menu (If you want to call one "XP Home Clean" or something) then right click on My Computer, click Properties, then go to the Advanced Tab. then click the Settings button next to "Startup and Recovery". then click the Edit button to change the name of your OS. Then click "Save" when done. This only changes the name shown when you startup - it doesn't effect anything else.
hope i helped!
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)