Windows 7 upgrade idea.... sanity check

I've been putting off upgrading from XP because of all the hassle it'll be.... but I need to do it.
 
I had an idea today that I want to test out with you.
 
Right now I have two HDDs in the tower.  Instead of backing up then wiping out the C drive to do a clean upgrade, I'm thinking maybe I could:
1) Disconnect the two HDDs
2) Install a new HDD or SDD and load Windows 7 64-bit onto that.
3) Reconnect the two HDDs but make sure to set up the boot order to choose the Windows 7 drive first.
Then if I ever wanted to reboot in XP I could.  (And yes, I'm assuming none of the programs installed on the XP drive would operate when W7 is loaded.  But I am assuming everything on my second HDD drive (that I use for media) would still be accessible under W7.)
 
Does that makes sense?  Or am I setting myself up for a world of hurt at some point here?
 
Thanks in advance.

Thanks Jim.  I really appreciate your advice; it carries a lot of weight.
 
Meanwhile, I clicked on your website and let out an audible "oooooo".  When I've eked out the last of this build (that I did), I'll be starting at StudioCat instead of DIY.