I'll Start by Bragging about my Video cards lol jks....well the 6200 is a very weak card. I understand that you can run Half life 2 Demo but that doesn't mean you'll be able to run these games unfortunately.
The graphics have been updated to match the new and fast evolving Next Gen games.
That being said, it doesn't mean you can't run them period. It might just be really iffy Frames. With all honesty weather your system can run it or not id suggest updated hardware (The Frames will be extremely choppy)
So what I suggest you do is try to get a hold of a copy of Half life 2 Lost cost. (which is a tech demo Program)
See whether your computer will be able to take the frames. another quick suggestion would be to atleast get more ram.
You should be able to run the game. but the Direct X 8 is going to be ify in this case.
Okay I read your above message with the update...I can't see the link.
To answer your question i don't see you getting over 30 FPS...and yes RAM WILL MAKE A HUGE DIFFERENCE
I had 512 ram a long time ago and I updated to 1 so i could play far cry...it changed everything.
here is a benchmark link...the Scores aren't good...but they aren't bad. You could prob reach 30-40 Frames but your cpu is a celeron and your ram is low. So I can't really gaurantee anything.
The Benchmarks you see on the website are done with a Way faster CPU and double the Ram.
http://www.nvnews.net/previews/geforce_6200/index.shtml