In short, if you have the ability to back your machine up, I'd go ahead and upgrade. You can go back if it doesn't work out.
I just upgraded my laptop to Windows 7. I did a clean install, but the only device for which I actually had to install drivers was my video card, and the driver I installed was a Vista driver; the included drivers are working fine for my other hardware.
I'd say that it's probably a safe bet that most Vista drivers will work in Windows 7. Although it was mentioned in a response the other question, I'll mention it again here; if you have not yet installed and run the Windows 7 upgrade advisor, do that. You can download it here.
If you have access to disk imaging software and an external hard drive on which to store the image, I would recommend creating a backup image of your laptop's hard drive. If Windows 7 doesn't work out, you can just restore the Vista image.
Clonezilla is free disk imaging software. You can download it and find instructions for it's use at www.clonezilla.org