Switching default hard drives?

[PcMe]

I just built my computer (yeeeeah), and I ran into an issue. I am using my previous hard drive, and it has incripted windows xp on it, even when I reformat it. So, I put the operating system on drive D, which is only like 2Gigs.
Here's my problem- whenever I try to dowload something or install halflife2/cs:source, etc, it always says I have too little space, refering to my disk drive D.
So how do I change the default to drive c? Otherwise I can't install my games until I get a new hdd

 

[sPlAtOiD]

Hi

So you could always use a windows 98 disk to boot from and at the a: typr fdisk.Then you could delete the primary partition.That will remove everything from the hard drive.Then create a primary dos partition and then format and install your OS on that drive...