you need to determine what's using all the space (music, photos, videos, games, etc.) so you can move the correct data. you can move most of your data files by moving the "Documents" folder for the main user. http://www.edbott.com/weblog/?p=1371
you can also move the files for many apps. for example, iTunes' library can be moved by the Edit->Preferences menu, in the Advanced tab.
of couse, you'll need to check the size of the folders' you're moving to make sure there's room for them on the D: drive.
also, check how much space system restore is using. by default it's 15% of the hard drive which is way too much for most folks. (on my laptop, that's 22GB so i scaled it back to 5GB.)
SOMEBODY PLS HELP!My daughter has got a 1 yr old Acer laptop(basic)running vista.We are running out of space on the C drive but there is 30gig free on the D drive.PPl tell me to move stuff over but I'll be str8 I aint got a clue!I got registry mechanic to help a bit but its not curing the problem.Can somebody pls explain in dumb azz terms how i can sort this as my daughter is nagging for a new comp now!!All help will be v.v.v.grateful! Daz.