You can upgrade your softmod to Krazie's Ndure 1.1.1 by using CASH ver 1.1. Just save everything you want to the PC first for safe keeping. Then do the upgrade.
You can also FTP the C and E drives to the PC and make the new HD first, then do the upgrade to it. That way if you mess up, you have the 80 gig you can still put in there.
If you get the 250, you should still be able to keep all the data on the F drive. I would use Xbpartitioner to format it in 32k clusters to be safe.