I used to build systems and do notebook repairs for industrial use so I'm confident in being able to do the upgrade with out issues. There is also a video that shows a complete dissasembly of the G73 that I've watched a few times and the process doesn't seem to be to difficult.
Both CPU's use the same socket so its just like changing any cpu, except I'll need new thermal paste.
If I have to take the whole system apart just to change the memory sticks then I might as well do the CPU at the same time is my thinking. It's purely a cost issue or I would just go straight to i7-2920XM but the 2820qm should be plenty.
Laptop:
ASUS G73SW
Upgrades:
Kingston HyperX DDR3 1866 PnP 16GB (4x4)
Kingston HyperX 120GB SSD
Seagate Momentus XT 750GB Solid State Hybrid Drive
Intel i7-2820QM
Desktop:
EVGA X58 3x SLI Classified, Intel i7-920, CoolerMaster V8 CPU Fan, 12Gb Corsair Dominator GT, 2x EVGA GTX 295 in Quad SLI, 120Gb OCZ Vertex 2 SSD, 3x Seagate Enterprise 500Gb HDD's, CoolerMaster HAF X, ULTRA X3 1000w PSU, Logitech G15, Logitech G9x, Dual 24" 1080p Monitors