It also depends on what resolution and settings you want to play the game at. There's alot of factors involved with getting good performance n a game, so please give us a little more information.
In any case I wouldn't expect Gears of war to run very well on an onboard chipset, even given a ram upgrade. I haven't played it since I upgraded a bit but on 2gb of ram, 8800gt, amd athlon x2 3ghz it would slow down considerably during cutscenes but gameplay pretty much locked at 60fps (max settings 1680x1050, directx10)
Minimum Recommended
Operating System Windows XP with Service Pack 2 or Windows Vista
CPU Intel Pentium 4 2.4 GHz or AMD Athlon 2.0+ Ghz processor Any Intel Core 2 Duo or AMD Athlon X2
Memory 1 GB 2 GB
Hard Drive Space 12 GB of free space
Graphics Hardware Nvidia GeForce 6600+, ATI X700+ nVidia GeForce 7600, ATI X1900
Sound Hardware DirectX Compatible
Network Internet or LAN connection required for multiplayer
Or so wikipedia says.
As for enjoying the game, I suggest taking a couple steps up from the minimum requirements, but that's just me.