Can't record audio: No Stereo Mix option (SigmaTel sound card, Dell Optiplex, WinXP)

[any ANONYMOUS forum user]

I have Dell Optiplex 740 and I want to record (video + audio) the games that i play on my system. And i don't get the audio as there is NO Stereo Mix option in the software driver provided.

It has SigmaTel Audio Driver. I am working on XP Professional OS.

I tried my best but could not find any solution.

I installed an LG driver for Sigmatel Audio Card suggested in another forum (downloaded from http://uk.lge.com/support/download_soft.jsp )
but it didn’t work as it showed some errors and the driver couldn't be installed may be because the drivers were for laptop and might be having some incompatibility problem with that.

I tried Virtual Audio Cable also. It was quite successful with small audio capturing but when I tried to capture some program for 45 minutes it resulted in audio flickers and misses at a lot of place.

Kindly help.