I tried the solution in the article yesterday, but it didn't help. Also, I got an error while executing the script:
asterisk:/Library/Parallels/Parallels Service.app/Contents/Resources tim$ sudo ./Uninstaller.sh desktop vitools gtoolsPassword:
can't open /Library/Receipts/Parallels Tools Audio.pkg/Contents/Archive.bom: No such file or directory
**** Can't open /Library/Receipts/Parallels Tools Audio.pkg/Contents/Archive.bom.
can't open /Library/Receipts/Parallels Tools Video.pkg/Contents/Archive.bom: No such file or directory
**** Can't open /Library/Receipts/Parallels Tools Video.pkg/Contents/Archive.bom.
can't open /Library/Receipts/Parallels Tools TimeSync.pkg/Contents/Archive.bom: No such file or directory
**** Can't open /Library/Receipts/Parallels Tools TimeSync.pkg/Contents/Archive.bom.
can't open /Library/Receipts/Parallels Tools HostTime.pkg/Contents/Archive.bom: No such file or directory
**** Can't open /Library/Receipts/Parallels Tools HostTime.pkg/Contents/Archive.bom.
can't open /Library/Receipts/Parallels Tools Shared Folders.pkg/Contents/Archive.bom: No such file or directory
**** Can't open /Library/Receipts/Parallels Tools Shared Folders.pkg/Contents/Archive.bom.
can't open /Library/Receipts/Parallels Tools ToolGate for Mac OS X 10.5.pkg/Contents/Archive.bom: No such file or directory
**** Can't open /Library/Receipts/Parallels Tools ToolGate for Mac OS X 10.5.pkg/Contents/Archive.bom.
nothing found to unload
[UN_OP]:Removing Guest OS Tools [UN_MSG]:Removing Guest OS Tools
[UN_PERCENT]:98[UN_OP]

ostuninstall Operations[UN_MSG]

erforming Postuninstall Operations
[UN_PERCENT]:100[UN_OP]:Uninstall successfull[UN_MSG]:Removed successfully
asterisk:/Library/Parallels/Parallels Service.app/Contents/Resources tim$
The error is obvious, I run Tiger, not Leopard.
The Parallels 3 installer still tells me Parallels 4 is installed. I'll download the v4 dmg and try the uninstall from that one.