Freeing up "unknown space" on my hard drive.

Last February, I bought a 320 GB hard drive to add to my computer. My main drive was 70 GB, but it was filling up fast with pictures and music. I also upgraded my XP machine to Vista Home Premium. I labeled my second Hard Drive X: (for extra). I pointed everything to my X drive. I told system restore and my backup to put everything there. This was the start of my problem which culminated here today. Over time, more and more of my hard drive was getting gobbled up. I was putting more and more photos, videos, and music on there too. What I didn't realize was that space was being gobbled up faster than what should have been. Here the other day, I finally dipped below 100 GB of free space. I started to look through everything that I had to see what I could delete. This is when I noticed that everything that I could see only totaled about 45 GB. Now, I have my virtual memory and IE Explorer cache using space on my X drive too, and I'm well aware that they gobble up some space. However, I was looking at a discrepancy of about 150 GB. I did some research into this and didn't find very good answers. I did the whole Shadow Copy route, but that proved unfruitful because my shadow copies were now being stored on my X drive, and no matter what syntax I was using, it wasn't recognizing any shadow copies on that drive, so it wouldn't delete them. I used the Windows Disk Cleanup utility and that proved fruitless as well. What I had to do was follow the procedures given on this link: CLICK HERE. I shut off disk backup and system restore first, then I rebooted. Once rebooted, I right clicked on my X drive and followed the procedures given on the above link. Once I followed those procedures for gaining full access over everything, my folder labeled OEM went from O bytes to about 150 GB. It contained two folders that were labeled backup and had some dates behind that. I deleted them and recovered my lost space. I'm not sure which combination allowed me to be able to see the files and to have access to delete them, but I know it wasn't the Shadow Copy route or the Disk Utility route. I had to do all that mumbo jumbo given on the link above and then shut my backup and system restore stuff off. I had to reboot. After right clicking on my X drive in the My Computer screen, I did the stuff from that link I just gave and only then was I able to find and see the files that I needed to delete. Since I now had full control, I could delete them easily and I freed up over 150 GB of space. If you find that you're having difficulty freeing up your "unknown space", try the confusing, but effective instructions from that link and hopefully you'll be able to free up your space as well.