Direct2Drive is an excellent way to download PC Games. You purchase the title with an account and then you download some very large files (2-4GB) in order to install the game. After installation, the first time you run the game you enter your activation code to activate the game online. This is much like Microsoft’s activation wizards. Once your game is activated, you never have to enter a CD or DVD you just play your game from your hard drive. It’s great!
I downloaded Splinter Cell 3: Chaos Theory and it has worked perfectly on my new computer with Windows Vista Business. The only issue I had was a driver from StarForce. Vista searched for a solution and found a website where I could download an updated StarForce Driver for Windows Vista. I installed it, restarted my system and Splinter Cell works perfectly.
Direct2Drive recommends you burn your installation files and activation codes to CD’s or a DVD for safekeeping, which I did as well.
So if you need a game right away and you don’t want to go all the way to Best Buy, this is your best bet. 
