Why not make your life a lot easier and just buy a second hard drive. They are so cheap these days, and will simplify things a lot more than all of these multiple partitions. Simply install the second drive and use it as a backup/download/crap collector/etc. You can even partition the hell out of it if you want.
This way you can keep your primary drive simple and your backups will be on the second drive, providing you protection against failure of the first drive. You can even set up automatic scripts to do backups on a regular basis.
If you ever have to reload your system due to virus/crap/etc, then all of your data is on the other drive and you can do a clean install very easily. This is what I do. I even go one step further and actually install the operating system on the second drive as well so that if I ever need to I can boot to the second drive simply by changing the BIOS settings for the boot drive.
Echo