I'm surprised the scan completed.  How does you scanner software do, does it have image resizing?

You memory cap at this poin is 4GBs of RAM, 2 for windows, and 2 for the program you are using.  I doubt you have 3GBs of Virtual memory allocated(Or you'd know you'd have done that.)  So, you may try bumping that up there:

Goto Control Panel > System > Advanced > Peformance > Advanced > Virtual Memory.  There you can make sure Windows Opens with and Maintains 3GBs of VM.  You'll then need to restart you computer, at whcih time you'll notice 3 less GBs of Free Space, but then you can give it another whirl.

I'd leave this task for before you go to bed, head out for the evenning or something.  Then you can probably ecpect to do much of the same, one your image editor gets it open, as that large a resize is going to take time.

Your best bet may be to try to just save it as a .JPG, before even trying a resize.  Even at the highest quality I bet you could knock the file size back under 50MBs.

TIFF is a large format.  People will tell you a 1.6GB TIFF is way too uge, you probably would'nt get a Print Shop to touch it.  Or anything over 300 - 350 DPI for that matter.