depending on your feelings about online shopping, you could check Newegg.com. Damn good prices, and I've never had a problem from them

If I was planning a definite replacement I'd be all for it. My only qualm about it now is that there's a fair chance, in my estimation, that replacing the graphics card just won't solve my problems, and if that's going to be the case I want something readily returnable.

I'm assuming that your machine is AGP only here since it's a bit older, these are the best rated 512MB cards under $150 from the current major lines:

http://www.newegg.com/Product/Product.asp?Item=N82E16814161052
http://www.newegg.com/Product/Product.asp?Item=N82E16814141026
http://www.newegg.com/Product/Product.asp?Item=N82E16814133176

Harddrive, assuming IDE and not SATA, is easy- space is cheap these days:
http://www.newegg.com/Product/Product.asp?Item=N82E16822145128

Sweet, they all look workable.

How big a drive do you need?

Small. I only need to cram it in to put a clean Windows install on. As far as I know there's nothing actually wrong with my hard drive, I just have no way to save the data on it to reformat/reinstall.