I wouldn't bother, it's all put together, like Muffin said, you could upgrade the CPU with some decent work. But the GPU is in fact soldered down in these situations. You're better off to ebay and buy new.
You can actually upgrade the gpu, it is in a MXM package (like PCI-e) and is a removable card. I think some people have successfully upgraded to a GTX260M from a similar model lappy (the G60 series) The cards look the same (Ebay). I was going to upgrade the cpu/gpu of my g50vt-x5 myself, but I just ended up slappin some Arctic Silver-5 on the NB/CPU/GPU (lowered temps a little bit) and ocin the cpu to 2500mhz and the gpu to 600core/1500shader/900memory (these are the actual clocks of the 9800m gts) And that raised my fps a little..... NOTE: I used nvidia control panel to OC, and I used setfsb to oc the cpu (the pll for the g50vt is Ics9lpr604aglf) I wouldn't recommend going over 240fsb...got a little unstable for me.
Actually, you can upgrade the GPU, though you lose fan control (stays at 100% RPM all the time) and no more audio through the HDMI port. You need to buy the specific heatsink for that GPU, so the GPU mount area and RAM areas and screw holes all match up.
The CPU is upgradeable too, to an X9100 and you can overclock it via Throttlestop to 3.45GHZ at 1.3125V so problem, 100% stable at full utilization.
With the CPU overclocked, and both the X9100 CPU and stock 9800gs GPU being fully utilized with Seti@home, the AC adapter is almost maxxed out but not quite. Power consumption is at about 120W so power converted is at about 105-110watts. Not a problem. Just keep the adapter cool enough.
Tips for increasing cooling of the laptop;
#1 Upgrade from the stock Delta KDB05105HB “7F36” 13 fin fan, to the Forcecon DFS541305MH0T “F8U5” 17 fin fan. It moves a good notch more air. $15 or cheaper shipped on line.
#2. Perhaps dremel out the fake subwoofer on the bottom and leaf it clear for airflow. This helps the temperature of the CPU/GPU heatsinks, but the rest of the laptop tends to run a bit warmer because now the fan isn't sucking air from all the little vents on the bottom of the laptop, but just the big hole.
#3. Use MX-2 heatsink compound when repasting after upgrading the fan. It is rated at 7 years of durability, which is important in laptops.
Upgrade the CPU. I upgraded to a Intel T9800 (2.93ghz) which is completely compatible but at a 35 watts instead of 25 so it pulls a bit more power, but suprisingly runs cooler at normal operating temp. Here is a list of processors that should work, but I would suggest either the T9800 or the T9600 as they are viable upgrades for relatively very little money now-a-days.
This is my list of what is supposed to work on the G50 - T6400, T6600, T9400, T9550, T9600, T9800, T9900, P7350, P7450, P8400, P8600, P8700, P8800, P9500, P9600, P9700, X9100