How do you switch from (C) drive to (D) drive

i recently had to system recovery on my computer and when the system came up ,it switched my hard drives from presario(C)52g and local (D)4g drives to local(C)4g and presario (D)52g drives. now all the programs go to (c) drive and there is not enough space. is there a way to switch the drives back to what they were or just switch the drive letters.

Try Disk Managment.See HERE (http://support.microsoft.com/kb/307844) and for complications,HERE (http://www.petri.co.il/change_system_drive_letter_in_windows_xp.htm)