An operating system update like this Friday's release of Mac OS X Snow Leopard is a perfect time to clean up your computer and start fresh. Let's prepare your Mac for this weekend's 10.6 upgrade.
To install Snow Leopard, all you need is the $29 Snow Leopard DVD, no matter what Apple says about the Mac box set. You do, however, do need an Intel-based Mac.
you can either go from Leopard using the $29 Snow Leopard upgrade disc ($5 off at Amazon), or go from Tiger using the $169 Mac Box Set ($20 off at Amazon). Here's Apple's full set of system requirements.
In short, there are two ways to get Snow Leopard on your Mac: upgrade and install over Leopard, or wipe your hard drive clean and start from scratch.