I have a 250gb harddrive and when i installed vista, the hard drive split in 2 partitions.. now one is unpartitioned and one is only 80gb. I want to know how can I merge the 2 harddrives to make it 250gb again? I'm going to install back xp.. so do I do it before I install xp? or during? and how?

-250gb (main hard drive)
-currently using vista but going to install xp after i fix the hard drive problem

If you are installing XP to replace Vista just run the XP install as seen here.

http://www.michaelstevenstech.com/cl...all.html#steps

10b: If the hard drive or partition has a previous installation of Windows you want to remove, choose to delete the partition by pressing "D". You will then be prompted to create a new partition in the empty space. This will remove all data from the deleted space.

You should be able to to create a new partition at this point to include your entire hard drive.

If you have any problems with this approach then Format your drive outside of Windows with GParted.