The 4.64 gb may be the Dell Recovery partition. Boot into Partition Wizard to rightclick>Explore it to see what's in it.
Did you do anything with partitions other except Shrink XP to install Windows 7?
If the Dell came with XP then it would be an XP Recovery partition and may not run now - you can try cueing it up to see: Dell Restoring Your Computer´s Software to the Factory Settings
You'll need to burn the PW CD ISO file to CD first to boot it, yes.
Then follow the steps I gave earlier to convert C to Primary, mark it Active, Rebuild MBR and if necessary run Startup Repairs to move the System boot files to C.
Once C boots and is marked System Active, you can boot back into PW CD to delete D and Resize C into it's space if you want.