If you have the i7-620M then yours should be the M17x R2. The original M17x came out with the Core 2 Duo/Quad processors. This is a good thing as you can upgrade to the i7-920XM or 940XM which will give you a performance boost over the 620M The best GPU you can put in is the AMD 8970M as AMD still have driver support for older cards andno need to mod drivers (you can even put in dual cards in crossfire if you want to). If you want Nvidia then the 780M would be the way to go but you'll need to mod the display driver for anything past the Nvidia 200 series and driver support ended a few years ago, I think the latest for the 700 series is 425.xx.  If you only have an old mechanical HDD then installing an SSD will be a huge improvement, but you won't really notice a difference during gaming. 
Hi, I have an 'old' Alienware M17x R1 which I got a long time ago. It served me well and now it seems to not handle the basic games that I want to play such as Skyrim and the sorts. It can play Crysis and dead space so I think it might just be that games are much more demanding now  I'm still saving for either a good gaming pc or a console so don't want to spend much and was wondering if I could make it able to tide me over until I do? I don't know what if any upgrades can even be done let alone worth it so I have listed the specs below. Please can someone help with what can be done? I'm looking to see what components can be upgraded including the GPU, RAM, and maybe the HDD and even the CPU although that's new territory for a novice like me  [NAME] I have read some of your other posts and you sound like you have a good idea where to begin. GPU - ATI Mobility Radeon HD 4870
M17x R1, Full upgrade