[quote name='Martinmz']Well I've done some shopping and got some specefications. It has a 3.33 ghz processor,nvidia geforce n7300 graphics card, one tb hard drive and 1GB of ram is that fine[/QUOTE]
Umm I think you got an answer a while ago, the HL2 and other Source games will run on your PC, but won't run well enough for you to enjoy gaming. 1GB of RAM is probably too low to run games, even in Windows XP. 2GB is the bare minimum nowadays. 7300GS is a low end graphic card, but it should run the source games at low resolution and low details. I'm assuming that 3.33GHz CPU is a Celeron D, which is a very weak CPU. So basically, you have 3 components bottlenecking your gaming experience, CPU, amount of RAM, and the lowly 7300GS video card.
Really the only way to find out if your computer can run the games to your liking is to.... actually run the games on your computer and find out yourself.