Hi RambleOn,
I would not delete that one. It is suppose to be safe, but everyone that did it had to do a reinstall afterwards to fix Vista. I would recommend that you do a Repair install ro fix this problem, then run Disk Cleanup to get rid of what you want.
Repair Install For Vista
This will show you how to delete one partition to use it to extend another one. Be sure to read the NOTE and WARNING at the top.
Disk Management - Delete and Extend
Shawn