Is it worth to buy a M17 when you have an Asus G73JH and an R2?

I like the M17x a lot it's just too heavy for the carry around on a daily basis and i really don't understand how they went from an m17 design to that and even the M15x is just really a huge desktop replacement. I like the G73JH a lot but you have to take apart the whole notebook to just to get parts and idiotic asus won't even allow you to change the gpu as it's a backwards design. I love led and rgbled displays a lot and i would like to own a precision again but it's like having the same computer and my money is pretty limited and i really don't want to sell the G73JH i just like having a variety of machines lol. I want something like the G73JH faster but with cross-fire and the M17 only fits the bill i would love to find a way to upgrade it to the ati 4850's i just worry about most of them don't have warranty one guy on the forums is offering it to me for 1,200 bucks with 1200P, cross-fire, QX9300, 4 gigs of ram and a blu ray drive and dual 500 gig 7200RPM drives and that's what i am looking for in terms of specs. How does the 3870's come up during gaming? I basically want a light enough machine like the M17 to take around for gaming and i never had an extreme processor before either. I run a lot of games and virtual machines at once. I am also wondering since the motherboard accepts MXM 2.1 graphic cards could they take these?
http://cgi.ebay.com/NVIDIA-GTX-280M-...item19c12be26c
Why are the 4850's so hard to find?

Also man it's been so so hard and difficult to trade with people i find it such an insult to tell me that i am going to screw someone up during a trade!!! I have never ever done that before and never will!

Damn man no help here for godsake cmon!

Hey its lighter than the r2 ill tell you that and so damn cheap I was looking at m15x and its just a rally large desktop I did see one with a 740 and gtx 460m. Dude do you think the 280m will really work in a m17 just pondering and yes your right they are harder to find. Thank you for replying also what type of graphics does the m17 mobo accept?