Confronting insurmountable os headaches, I elect a re-install. My inherited sys has a 2nd hd on which a copy of WinXP Home (my os). Two questions: Assuming this is a copy of my pre-headache os, can I use it instead of a complete re-install? And, how do I access it to determine if that's so?

Secondly, since this #2 hd has sufficient space, couldn't I just back up my essentials here preparatory to an os re-install as opposed to a cd, external media, etc.? 

 Dell Dimension E310
WinXP Home SP2
1GB DDR2 RAM
80GB Hard Drive
Intel Express Chipset 3.6 GHz