AW computers, even used and older, are not discount bin products. For whatever reason, AW's hold their value.
I disagree people are willing to pay for the name alone. The cases are unique, and Alienware computers tend to be fast enough to outlive other laptops that seem to need to be retired yearly due to the fact that most laptops are slowwwwwwwww. A couple year old Alienware will still outperform most laptops easily in games and multimedia.
I'd keep it myself DB, unless you need the money. I have a 5500 with the 16.1" screen, 3.4 P4, and ATi 9700, and I've been playing GTA San Andreas on it for a while now, and taking my mp3's and some movies with me to my chemo appointments. I've never sold any of my Alienwares, I just don't need the money, and the hassle of selling isn't worth it for me. By the time I might be willing to part with them, they still aren't worth selling. You thought about trying to buy, beg, or steal a 9700 to slap in that thing?
Also, I kinda like my little collection of AW history.