No, there are 2 other settings, com_soundmegs, and com_zonemegs, but buggered if I know what they do. The point is all 3 added together is how much memory ET uses, but with 1Gb RAM you shouldn’t have any problems in that regard, and it’s hunkmegs that sometimes needs to be upped to play customs. That isn’t your problem by the looks of it.
Just to show that I’m not an unsympathic git, I had major problems with RTCW once upon a time. Everything else (well Half-Life based games) played fine, but RTCW kept crashing my PC. I tried different memory, different drivers, different sound card, no sound card, re-installtions, everything. Went back to bare bones hardware / OS, added each component and tested, and got no-where.
I then upgraded motherboard and processor and haven’t had a problem since. I’m convinced the original motherboard wasn’t supplying quite the right voltage to the Graphics card, based on extensive research at the time, but my old mobo didn’t provide any means of adjusting it.
Not that I wish you to give up hope, but there are just too many hardware configurations possible for anyone to guarantee their software will work without error on all of them. Maybe, in hindsight, something along the lines of “this is my problem, these are my specs, grateful for any assitance” might have been a more appropriate opening post?