hii I'm a beginner in this

I have dell vostro 1500

DELL Vostro 1500| CPU: Intel Core2Duo T8100 | Ram: 3 GB DDR2 | Intel® P965 Express Chipset GMA 965 + X3100 | HDD: 250 GB| AppleBCM440XEthernet | Windows 7 Ultimate & Snow 10.6.4

I've installed and dual-boot with windows 7 64bit snow leopard 10.6.3 and update it to 10.6.4 but the display still the same resolution 1024x768

I want it to be 1280x800

this the info from windows 7

Name Mobile Intel(R) 965 Express Chipset Family
PNP Device ID PCI\VEN_8086&DEV_2A02&SUBSYS_02281028&REV_0C\3&18D 45AA6&0&10
Adapter Type Mobile Intel(R) 965 Express Chipset Family, Intel Corporation compatible
Adapter Description Mobile Intel(R) 965 Express Chipset Family
Adapter RAM 384.00 MB (402,653,184 bytes)
Installed Drivers igdumd64.dll,igd10umd64.dll,igdumdx32,igd10umd32
Driver Version 8.15.10.1930
INF File oem6.inf (i965GM0 section)
Color Planes Not Available
Color Table Entries 4294967296
Resolution 1280 x 800 x 60 hertz
Bits/Pixel 32
Memory Address 0xFEA00000-0xFEAFFFFF
Memory Address 0xE0000000-0xEFFFFFFF
I/O Port 0x0000EFE8-0x0000EFEF
IRQ Channel IRQ 16
I/O Port 0x000003B0-0x000003BB
I/O Port 0x000003C0-0x000003DF
Memory Address 0xA0000-0xBFFFF
Driver c:\windows\system32\drivers\igdkmd64.sys (8.14.10.1930, 5.89 MB (6,180,832 bytes)

and this from OS X SL 10.6.4

Type: GPU
Bus: Built-In
VRAM (Total): 64 MB of Shared System Memory
Vendor: Intel (0x8086)
Device ID: 0x2a02
Revision ID: 0x000c
Kernel Extension Info: No Kext Loaded
Displays:
Display:
Resolution: 1024 x 768
Pixel Depth: 32-Bit Color (ARGB8888)
Main Display: Yes
Mirror: Off
Online: Yes

It proves this:

Chameleon 2 RC4 patched with 915resolution for Snow Leopard and Intel GMA X4500 « Deviato