Studio XPS 16 help

Hi there Dell community.

I purchased A dell XPS 16 for a good price towards the end of 2010, however I am wanting to update the graphics card if that is at all possible. The specs are as follows.

System Model:    Studio XPS 1645

System Type:    x64-based PC

Processor:    Intel(R) Core(TM) i7 CPU   Q 820  @ 1.73GHz, 1734 Mhz, 4 Core(s), 8 Logical Processor(s)

RAM    4.00 GB

Disk capacity:    451.07 GB

Graphics: ATI Mobility Radeon HD 565v (1gig)

This laptop has been fantastic and has had no problems so far, however I have recently wanted to update the graphics for gaming purposes as it seems to be the only aspect that lets the laptop down in terms of performance.

Are they all integrated and soldered to the mother board or is it possible to change them? with obvious consideration for the power supply and adapters needed. Even if they are all soldered, is it not possible to re-solder another card in and just install it via the disk and device drivers? It's a shame that it falls behind in only one area but is very current in the others. I selected the highest graphics option when I purchased the computer hoping it would cope with today's current software and games, but it seems my thirst is yet to be quenched.

Any enlightment would be appreciated because I do not particularily want to purchase A) a very expensive pure dedicated to gaming laptop (Alienware) or a Desktop gaming rig. Considering I don't play games all that regularly it seems a waste to put an extensive amount of funding into a new system as opposed to updating one component of my current setup.

I Look forward to the replies.

Cheers