We're not going to upgrade to 2010 yet - it is not an option. My laptop with XP just crashed and I need to buy a new one.
The Dell salesman is saying that compatibility mode will run any 32 bit software. Quite a commitment based upon his word.
Is anyone actually doing that successfully? I'd really rather not buy Vista Home Premium if I can help it.
I recently installed Windows 7 Pro (64-bit) on my system (new hard drive), and installed v2009 on this system, though SolidWorks says it's not supported. I'm running SP 5.1 now, and it seems to work fairly well (more glitchy than my XP install, especially with assembly configurations where parts are suppressed).
If you'd like to see more about what I've seen with all this, check what I've posted here:
https://forum.solidworks.com/thread/32276?tstart=0
This is mostly an aggregation of things others have posted that helped me get things functioning in Windows 7.
As for "compatibility mode" particularly, I've really not encountered this as an overt part of Windows 7. When I install 32-bit software, it simply gets installed in the "Program Files (x86)" directory automatically. The only thing I've really tweaked was the SWIM for updating service packs for v2009 on my machine, as detailed in the post above.
Good luck.