Seeing as you ordered the upgrade version, I'd wager that you can't do fresh installs of either the 32- or 64-bit version. Granted, I've never used an upgrade version, I've always done the full retail or OEM version, so I can't say for sure.
Aside from that, I don't see any problem with a quad-boot. Just partition your drive as many times as you want. I find it easiest to do on a single HDD, but that's just for my own convenience. And the Wubi installer makes for a great multi-boot solution for Ubuntu.