Don't reinstall / repair -- depending on how it is done it might just repair damaged files but leave everything else intact (including the pron aidz). Clean this thing up with a complete Format and start with a Virgin fresh system.
I haven't done this with Vista but with XP it is something like this (from memory):
-Before doing anything, save yourself some time and find out what hardware is installed (video cards, network cards, etc) and go download the latest drivers and burn to a CD from a "clean" computer (other than your pron computer).
-Boot from the Vista CD making sure you have a valid product key before starting (may need to set the BIOS to boot from CD).
-Depending on options presented select "Install" rather than "Repair"
-At some point it may ask if you want to use "existing partitions" or "delete and re-partition" -- choose re-partition.
-Now you may have a choice for a "quick format" or "full format" -- choose "full format". Quick only wipes the FAT table and leaves old data in place while Full format blows everything away.
-Let 'er rip. Will probably take about 45minutes or so to install.
-After installed, use the driver CD you created before starting the process to update the drivers for optimal performance.
This is probably missing a few steps, as I've never done this with Vista, but you get the point.
For mor help Google is your friend. Here is a helpful link for installing Vista:
http://www.youtube.com/watch?v=FVbf9tOGwno
I keed, I keed --
try this one:
http://www.buildeasypc.com/sw/windows_vista/install_windows_vista_p2.htm