Hello, I am newbie here, and I hope you will help me

. I have lenovo 3000 n100 laptop, everything was good, but I had to change motherboard because of damage. And only later I realised that new motherboard have internal video card.
It ca have memory of 256mb, but now it has only 8mb! I have readed that you can change that memory parameter in bios. But in bios i can't see theese settings.
So request: hidden advanced menu, to change internal video card parameters.
-Manufacturer: Lenovo
-Product name: 0768FXGL3TM141
-OS: Windows XP professional x32
-Motherboard Model: I dont know where to look
-Bios revision: 61ET37WW (V2.06)
-Bios Type: Phoenix BIOS Setup Utility
-Bios Download Link: download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/63af08us.exe
(It's auto-extracter.)
Have a good day!