the thing with alienware is that the prices have skyrocketed and the parts are now cheaper as it is now owned by Dell. this is not such a bad thing and a gaming computer would still rock with Alienware... you are just paying for the name.
Id tell you to build your own computer, like i have, but if you do not have the means to do this (or the know how) Id recommend looking at these:
Top 10 Performance Desktop PCs | PCWorld
If these are too out of your rang, you can check check if anyone in your area is selling theirs or something more like these sites:
Newegg.com - Desktop PCs,gaming computer (newegg) or NCIX.com
Portal on high is cool but crysis two on full ;) oh baby... Im having a blast on Darkspore at the moment. Tried it on my laptop (really old + more for video editing) and it sucked... Good for you :P you wont regret getting a gaming laptop <3
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edit:
if you want, PM me and ill send you the parts i used for my computer :)
it has 8gbs ram, 2gbs video grapics and is a sexy beast <3
mind you, i spared not a cent on this rig. It will last years and out preform anything :3 (it wasnt cheap i mean xD so depending on how much u are willing to pay... you could build ur own, or get it made or just get an alienware or whatever :P )