Cannot Auto Install The Update

WinXP SP2 home
This system was loaded with malware such as Websearch, Wintools, Myway, and Ebates. I cleaned it out by:

1) Emptying %temp%
2) Disable System Recover
3) Reboot
4) AdAware SE Personel
5) Reboot
6) SpyBot
7) Reboot
8) HiJackThis
9) Reboot
10) housecall.trendmicro.com (new Beta version)
11) Reboot
12) Empty %temp%
13) Re-enable System Recover

I have re-run AdAware, Spybot, Housecall and even done a WinXP CD repair with all reporting that everything should be OK. Still, whenever I open Explorer (either one) and each different folder in Windows Explorer a couple of succesive "Windows Installer" windows pop up with "Preparing to install" and then they close without anything else. Also, there is very little that can be installed now. Norton Internet Security reports that it can't be installed now. Windows Update gives an error after you tell it to install the updates or display the detailed updates. Sun's Java says that there is another install that has to be finished first. Messenger says that it has a new version that has to be installed before you can use it but after it runs for a while it reports that it can't be installed.