I'm pasting my original reply here since the original post was moved here:
Infineon is definitely NOT "cheap RAM"...it's one of the best brands available. Infineon used to be in partnership with Siemens ("Siemens/Infineon") but since have gone off on their own, IIRC.
Anyway, I doubt your Infineon is causing any problem because it's "cheap."
I can't tell you anything about the P4 because I have a AMD T-Bird myself. Also, I'm not a gamer so can't help you there.
Good luck,
John D.