Using gpedit.msc group policy editor to prevent the use of software in the Guest account.

In Control Panel > Users, add a password to your account, and enable the guest account if not already enabled.

The following excerpt is from this link:
http://support.microsoft.com/?kbid=323525

"Editing the Local Policy on a Windows 2000-Based Computer
To restrict users from running specific Windows programs on a standalone Windows 2000-based computer: 1. Click Start, and then click Run.
2. In the Open box, type gpedit.msc, and then click OK.
3. Expand User Configuration, expand Administrative Templates, and then expand System.
4. In the right pane, double-click Don't run specified Windows applications.
5. Click Enabled, and then click Show.
6. Click Add, and then type the executable file name of the program that you want to restrict users from running. For example, type iexplore.exe.
7. Click OK, click OK, and then click OK.
NOTE: If domain-level policy settings are defined, they may override this local policy setting.
8. Quit Group Policy Object Editor.
9. Restart the computer."

You will notice that there's also a "run only allowed windows applications" option, use whichever is less work!

I believe you will need to disable these options in order for you yourself to have full access to applications once again.

Is there a way to apply this to the Guest account only, in XP Pro?  Im using XP Pro.  Is the answer that I deny all users the permission and then give myself access?  That seems to be too difficult in a way.

here's a thread that mirrors our conversation here, interestingly enough:
http://www.resellerratings.com/forum/t35489.html

...this thread discusses how you can possibly accomplish this through the registry (i want to research this more)...
...and how you can accomplish this through a program called 1st Security Agent http://www.softheap.com/newadmin.html (which incidentally gets 4/5 stars from CNET download.com). if this issue was important enough to me, i would pay the $49 for the program rather than play with the registry.

so, at least we know that we're not the only ones struggling with this, and we know there's a program out there that will do this for you (and it appeared to be the only one on CNET). i'll try to look into the registry method, though.

Ok AZ, that sounds fine.  I will research the site.  Yes, if you want to, feel free to post the way to make the registry change.  It is up to you however, since it seems it would be pretty tedious to do this.  I of course take full responsibility if i wreck something.