You can run them the same way you could run them on a system with 512 MB of ram @ 333 with a 64 bit integrated graphics card. A more useful question would be what settings could you run them on, to answer that question i need more detail like the speed of your ram and maybe the name of your processor or at least the company.
The CPU will kill you and the GPU will too. You can RUN the program, but I doubt it will run where it is playable. Don't be surprised to see below 15 FPS in GTA IV.
Mass Effect 2 will also be hampered by this system.
For GTA IV, you really want a quad-core (or even a tri-core from AMD will work). The graphics card really needs to be updated as well.
I beg to differ. I am running an Intel E6300 and nVidea 9600GT with 4GB DDR2 RAM. I CAN run GTA 4 on medium settings.
Yeah, but the 8600 is what he's running as far as a GPU. The 9600 is better so it's probably helping but still, a quad core will get you the best performance. I'm not saying it's absolutely necessary, but it does help. GTA IV has been programmed to take advantage of CPUs with 3 or 4 cores.