primary and recovery(backup) drive switched what do I do?

The C:\ drive on my home computer with 100 gb has been made the recovery drive, and the H:\ drive,a partition with 4.44 gigabytes has been made the primary. The computer always says system memory low so I cant install new programs or run programs that require lots of memory. I dont even have enough memory to do a system restore. The computer, I think, boots of the H:\drive and that is what is causing the problem. The C:\drive is partically still empty, It still has 75 gb of free space. Is there anything I can do to resolve this problem. Please try to decipher what I am trying to say and help me. Thanks