I was thinking if I had to reinstall windows, I could then keep those from being deleted, since everything in windows folder would be gone.
What is the nature of the WTV recordings you currently have 1/2 TB of? If they are TV recordings from your cable company, and are copy-protected (which almost all are depending on your cable provider), you will LOSE THEM ALL if you reinstall Windows. This isn't because they got deleted, but because the DRM (digital rights management) encryption of those copy-protected WTV recordings can only be played back by WMC running on the exact same installed Windows that did the recording in the first place. Installing a new Windows creates a new encryption/decryption key which is 100% useless for your old copy-protected WTV recordings. Period.
Now as far as simply getting them off of C, you really should probably have a second drive for "data". You than just define this second location to be part of the "recorded TV" folder structure for WMC, for playback. This "recorded TV LIBRARY" can be one or more folders (which will automatically get named "\Recorded TV" and that you can't change) spread across one or more drives.
In contrast you can only have one "primary recording" folder (also named "\Recorded TV") which is somewhere on some drive. There is no "pool" of multiple folders available for recording, as there is available for playback. So if available space in that one recording folder (on that one drive) becomes an issue, you will need to manually move WTV recordings to some other one or more "playback folders" yourself in order to free up space for new recordings in the one-and-only "recording folder".
That's why it's recommended to have almost a dedicated large-capacity drive (with good performance, so large cache and SATA-III and 7200rpm) for your "recording folder" which by definition is also your first "primary playback folder". This ensures you won't run out of room making new recordings. If things get critical (e.g. during the two weeks of Olympics recordings, when HD recording is almost continuous and possibly from multiple channels), you need to also have extensive secondary "playback folders" capacity, and manually move (with Windows Explorer or whatever) your recordings so that you still have them for eventual playback but still have available capacity for new ongoing recordings.
NOTE: since \Recorded TV is in the root of a drive, you can only have one of these folders per drive. So if you need enormous capacity you need multiple drives, one "dedicated" for new recording, and one or more in the "playback" LIBRARY pool, each drive containing one \Recorded TV folder.
Nevertheless... if you have copy-protected content, you WILL LOSE USABLE PLAYBACK ACCESS TO IT if you install a new Windows. Period. On the other hand, if this content is copy-freely content (either OTA/ATSC or delivered copy-freely by your cable system) then you can do whatever you want with no restrictions at all. That's why it's called "copy-freely", because it is not copy-protected.