help with moving mw2 pc install

Okay so I got mw2 for the pc installed on my laptop, it runs good but not that great...since It has ati radeon 4200 graphics which make it lag on high settings

I left for college 2weeks ago and I left my mw2 install cds at home and I forgot where I left them and my folks can't find them

I am about to buy a desktop for my dorm and I am wondering if I can move the install using an external harddrive from my laptop to the new desktop

if anyone can tell me how to do this it would be apreciated.

btw is this desktop good?

for $449 I am getting an HP with:

AMD Phenom Quad ( dunno if I spelled it right)

6gb of ram

640gb hard drive

built in wireless card ABGN

and nVidia 9100 graphics with who knows what

Thanks

Well, without actually doing any research, I'm semi certain that the 9100 isn't any/much better that the 4200 laptop card. The low pricetag on the desktop is kind of a give away that it isn't that great.

Also without any research, I really don't know if you could but i'd guess that they'd put some safeguard on the game to prevent you from doing something like that.

Or I could be completely wrong but that's what you get for not google-ing it your self

Ummm so could you tell me how do I do that?

I really never had anything to do with steam til mw2 came out

so redownloading would be a good alternative( all I need to have is my steam id and password right?)

also then what graphics card should I buy for that desktop?I would have an extra $150 if I buy that desktop and out here theres really not much to look at :/