Current version of Vista broken, can I just reinstall and preserve files? Or install to different partition?

So my Vista stopped being able to boot, if I install a fresh copy on the same partition as I had it before, will it format the partition, thus deleting all my files? Or will it simply reinstall Windows and leave my docs alone? Or the other option, I have another partition that I can install it to, if I do that, will I be able to access the partition with the old version of Vista on it and my files (that way I can just drop all my files to an external HD).

Thanks!

here is what prompted the whole problem:
I have a XPS M1210, Vista Ultimate. No previous problems. I typically don't use Media Direct although I did set it up a few months ago. Last night I accidentally pressed the MD button when the system was off and the MD software began loading. It froze, I pressed and held the power button to power down the system. Then I pressed the power button to boot it up. It went through the Dell screen and right before it was supposed to load Vista it flashed a quick blue screen and went back to the Dell screen that appears when you first turn on the system. Then it gave me the option to boot normally or into the diagnostic screen. I tried loading normally a few times but it kept bouncing back. I ran the auto repair function in the diagnostic menu, the auto repair stated that it found and repaired a hard drive error. After this I tried to power on again. Now it goes past the Dell screen, past the Vista loading green bar but then gives me a black screen with just my mouse cursor visible. I can press CAPS lock and the keyboard responds, but ctr alt del doesn't work. I turned it off (by holding the power button) and tried to get into MD, it gave me the same black screen with my mouse cursor, but this time I could press ctr alt del and bring up the Task Manager. I ran the various hardware diagnostics and all of them came up OK.

 

Have you tried pressing the MD button to turn the power on? During a failed MD boot sometimes mine will swap the normal power and MD buttons until I get a good load. Try powering up using the MD button a few times and then try the normal... I am not sure what fixes it but usually I can get back to a normal boot.

This probably does mean your MD partition is hosed though...

Do you have a lot partitions?

 

I've tried to press the MD button, no change, just takes me into MD. I have 3 partitions, the main one, the MD one and the dell recovery one. My main goal is not to lose any of my files. If nothing else, I think I'll format the MD partition and install Vista there as I mentioned in my 1st post, I just need to know if that makes sense to do...