Whenever I try to install gears I get an error message. Any help would be appriciated.

My computer is as follows:


Processor:
Intel(R) Core(TM)2 CPU 6320 @ 1.86GHz (2 CPUs)

Memory:
1006MB RAM

Video Card:
NVIDIA GeForce 7300 GS

OS:
Windows XP Home Edition

Basically, I don't, and can't possibly make enough space in my C drive to install gears, because the space is only there for my documents (which are empty), and critical windows files. All installations go to my D drive. When I try to install Gears to my D drive, it comes up with this:
http://i36.tinypic.com/2zdtx8x.jpg

saying that I need 7,675,225 KB available in C. I specify that I want the file in D, so why is this happening?

Can anybody help?