This isnt something youre going to be able to fix on your own. This particular kind of virus is pretty wicked. You can stop it from runing but it will more than likely tunnel into your system files and cause a world of problems. The zbot is a backdoor trojan, its going to open up a lot of communication ports and start sending messages. You should stop using this computer, go on a known clean computer and change any banking/email/messenger account passwords. Then bring your computer to a certified technician and have them repair it.

You can use the registry editor to delete these values, but more than likely theres a lot more registry entries containing malicious instructions. Its safer to bring it to someone who knows what theyre doing.

Here are the two registry values i could find on this particular virus. If you delete these values the program thats infecting your computer will not run anymore but the damage is already done.

HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\WINDOWS\CURRENTVERSION\RUN\ XTray.exe
HKEY_LOCAL_MACHINESOFTWAREMICROSOFTWINDOWSCURRENTVERSIONRUN XTray.exe

If you have any questions feel free to send me a pm.

Try a system restore to an earlier date.