Counterstrike Source wont install...

I just got counter strike source for my birthday and it wont install its saying that i need 4.0.gb's of space i just got a new PC not to long ago and barely have any Sh*t on it :l can someone please help cause i really really want to own some newbz on CCS....

Try going into the CD drive and running the setup.exe (or whatever its called) in compatibility mode (Right Click> Properties> Compatibility> Check the box called "run the program in compatibility mode for" and scroll to windows 2000 or 95 [xp might work too]) Also make sure, if your in vista, run it as an admin, and make sure its trying to install to the right drive.