I have the exact same problem.
I'm using an Acer Travelmate 8571 Timeline with 4500 chipset. I've installed the latest drivers and also get horizontal lines/artifacts.
If I use the standard VGA Win 7 drivers, the graphics are fine (no artifacts, but slow, no shaders, etc), though as soon as I install an intel driver, the artifacts return.
Please provide us some help, because working on this machine with those drivers is impossible as is, and working without isnt a real solution, either.
I have exactly the same issue with a Dell Latitude E4200 (GM45) under Windows 7 (32 & 64 bits). Some people reported the problem comes from the amount of RAM. You need to have the same amount of RAM on each slot. Unfortunately my Dell E4200 has 1GB soldered on the mainboard and 2GB on expansion slot.
Could we get a feedback from Intel staff? It's a very annoying issue.