HDTV on a laptop??!! Video card problem?

I have a fairly new Acer Aspire 5100 with an integrated ATI Radeon xpress 1100 integrated video card. The system is running XP (I have no plans to upgrade) and has 2.5 G of RAM.

I have a Hauppauge WinTV-HVR 950 TV tuner stick that I use to watch digital television.

But, the digital signal is choppy and interrupted which I know is a result of the demand on my CPU.

I cannot afford a new laptop JUST for watching TV. And, before you ask, we don't have a DTV. My kids use the TV we have as a video player, and I use the computer to watch my "grown-up" programs on primetime in the evening. Weird, I know, but it is a system that works for us.

Anyway, questions:

Is it possible to upgrade the video card in an ACER Aspire? I know that newer laptops sometimes offer this as a possibility. Since it is integrated, I am thinking "no", but I thought I'd be sure. It has a PCI Express BUS according to my sys-information, but maybe that does not mean the same thing as on a desktop system.

If I add more system memory will that improve the choppiness AT ALL? I have read that I might possibly be able to allocate more RAM to the card by increasing the memory and then updating the BIOS files.

I have an open PCMI slot. Does anyone know of any extrenal PCMI graphics cards that would solve this problem without messing with my integrated graphics?

Is there a software fix for this? I have read that the bundled WIN-TV software sucks, but I am not certain how that could possibly have an effect on decoding speed.

Thanks in advance for any help you can offer!

HMama