|As above you are posting in the CPU/Overclocking forum, you should have posted in the Windows 7 forum.|
You can have up to 4 primary partitions or 3 primary partitions and one extended partition with many logical partitions within the extended partition. You should have a Boot sector (not usually counted as a partition since it is used before accessing operating system), your main partition with 'C' drive on it, and a recovery partition (your 'D' drive) which will allow you to reinstall windows in the event of a major OS problem (should be left alone). Unless you have more than what you are telling us, or a partition of minimal length due to a failed partition attempt (delete), you should be fine. Look carefully at Disk Manager to see all partitions there. You should not delete your recovery partition, especially if you have not yet made a recovery DVD from within windows. If you shrink your 'C' drive in Windows 7 with Disk Manager, your Linux installer should be able to create the partition(s) in the unallocated space if you truly have not reached the limit. Since a proper linux installation should have more than one partition, make it an extended partition so you can then create as many logical partitions as you need for Linux (Linux does not care if it is on a logical partition).
You have to be a little bit crazy to keep you from going insane.