I could help but the term 'Popular games' is to vague the most popular game in the world , known as world of warcraft only requires 64mb Grphx card, yet the extremely popular Battlefield 2142 requires alot more power than that. Or middle games like Call of duty 2 run quiet well online with average components
im running CoD2 on the following (i am soon upgrading)
25GB 2mb cache HDD
1GB Budget Ram
Creative Live 24-bit audio.
Very Old motherboard.
Please be more specific and i will gladly help, in a perfect situation you could helpfully list the games you will be looking to play.