Currently have a NVIDIA® GeForce® G100 in an Acer pc. How much of an improvement would the HD4350 be?
GIGABYTE GV-R435OC-512I Radeon HD 4350
what is the purpose? I didn't find the 4350 that capable for HDTV. The 4550 is a better option.
It's about the same. As autoboy said, it is in fact underpowered for top quality deinterlacing of 1080i. I'd leave your G100 as is if you aren't going to consider moving to a 4550 or better.
FYI: The G100 is basically just the new product name (to match the GeForce 200 product naming scheme NVIDIA started last year) for what was previously the GeForce 9400GT.