Start/Programs/Accessories/System Tools/Disk Cleanup to get to those files, AKA your cache. However, if you just tell it to clean up, it leaves the cookies, and tells you there are no files in the folder by saying "0.00 MB" -- obviously not true.

Highlight Temporary Internet Files and click View Files at the bottom. A Windows Explorer-type window will open. Click Edit/Select All and hit your delete key. Your box will freak out and ask you if you're sure you want to delete the cookies. Click Yes. You have just TOSsed [1] your Cookies.

[1] TOS for my box, that is -- *No Cookies!*