I have a work around that allows access to purchased content with Safari and/or Quicktime 7.7 installed, but it's not for the faint of heart. It basically involves copying the *.dll files out of the "C:\Program Files\Common Files\Apple\Apple Application Support" folder when version 1.5.2 is installed and then upgrading to version 2.0.1 (Quicktime 7.7 or Safari 5.1).
As such I don't recommend you do this unless you know what you are doing, otherwise you will likely have to completely uninstall and reinstall iTunes (or worse). If you mess things up, don't come to me for help. You've been warned.
I tested this on Windows XP, but it should work under Vista and 7.
Whenever you want to access your past purchases do the following:
1. Make iTunes, QuickTime and Safari are not running. Basically no Apple programs.
2. Backup all the *.dll files In the "C:\Program Files\Common Files\Apple\Apple Application Support" folder and put them in a safe place. I zipped them up.
3. Now delete all the *.dll files. I simply made a "tmp" folder inside the Apple Application Support folder and moved them there.
4. Take the *.dll files you save from version 1.5.2 and copy them into the folder.
Now you can run iTunes and access the store and download your past purchases. Leaving things like this is bad for a number of reasons, so when you are done simply quit iTunes and then remove the 1.5.2 version dll and put the 2.0.1 dll versions back.
Technically you don't need to replace all the *.dll, only about 10 of them, but it's just easier to replace all of them. Also note that there is one .dll file that is exclusive to 1.5.2 and 5 that are exclusive to 2.0.1.