Adding more Gigs to C Drive?

Hello,
hey guys my name is Parth.
I have windows XP SP2, and 250GB Sata Hdd.
My C; drive contains of 10 gb space due to the foolishness of the PC assembler. yes i got an assembled PC. the C drive contains nothing but system components and d drive contains all the programs, games, data, etc etc.
The problem is when i installed Adobe Creative suite the shared componenets got installed thus reducing the space further on C drive. now whenever i use the programs the error comes the i m running low on disk space, click here to free some space. when i do that i hardly get 350 mb of free space which gets filled up quickly when i start using the adobe programs again, calling for the same error again. This has been bugging me for some time but can anyone tell me a way to free up my disk? I tried all methods to free unuseful data on c drive to an extent that now not even 1 unwanted data remains on C. i dont want to format my hdd coz i got 170gb of data that is very important to me as a graphics designer on D drive.
So my question is "Can i add more gigabytes to C: drive without having to format my PC?"
please i need help.
thanks in advance :)