I am ahving a problem updating windows defender definitions, I run xp home sp2, have deleted and reinstalled but still get the same problem, I don't know if it will fix it if I update to Internet Explorer 7, but really don't want to install that version, anybody have an idea where I can start or should I just delete forever???????????

When the update fails, do you get an error code reported? If so, what is it?

There's a Windows Defender newsgroup here:
http://www.microsoft.com/athome/security/s...5b-565a73822c7f

where, almost certainly, someone will be able to help.

You could use the Windows installer Cleanup Utility to completely remove the program. Then reinstall.
http://support.microsoft.com/kb/290301

If you want to replace it, I can suggest some free program combinations that I consider better than Defender. Such as Spybot with teatimer enabled, Spyware Blaster and Super Antispyware free for the home user.

I don't think updating to IE7 will help. Using Firefox with NoScript extension is the safest way to go.