What model is your Presario?
BTW, no you won't be able to use your 6600LE and your integrated video at the same time.
It would help to know what socket and chipset you use. Download CPU-Z
and run it to get that info. Under the CPU tab, PACKAGE will tell you the socket type and under MAINBOARD look under chipset.
Also how much video memory does your 6600LE have (128MB or 256MB.) Either way, the lag is most likely caused in large part by the videocard itself. The 6600LE is the lowend version of the 6600 cards. It has half the pixel pipelines of the other 6600 cards (4 vs 8 on the other cards) and I'm thinking you are using the AGP flavor.
I forgot to ask which games you are getting lag on.
<font size=-1>[ This Message was edited by: VioletSkye on 2006-07-03 23:56 ]</font>