My company owns Illustrator as part of CS2. The guy who edited the Illustrator files has left, so I needed to install it on my PC. I didn't find a post that described all the steps I had to do to get it to work, so I'm posting my notes.
1. Download the updated installer from http://www.adobe.com/downloads/cs2_downloads/ to c:\cs2inst.
2. Run CreativeSuiteCS2Disc1.exe. This will put the contents of CD 1 at C:\Creative Suite CS2.
3. Do the same for discs 2, 3, and Extras, which will add more files to C:\Creative Suite CS2. Disc 2 had trouble finding that directory, I browsed to and selected it and it worked.
4. Run C:\Creative Suite CS2\Adobe Creative Suite 2.0\setup.exe.
5. Follow the defaults to install in the usual manner until prompted for Installation Location. Enter c:\adobecs2, click Browse, browse to c:\, create c:\adobecs2, and select it. (I found a tip to use c:\progra~2, which is the short name for "c:\Program Files (x86)", but the installer complained that the directory was read-only.)
6. Complete instalation as usual.