PCI express x16 question

Hi,
I am currently building a system for a friend of mine. Graphics are not a big priority for him right now. I bought a Biostar NF61V mobo off ebay (haven't tested it yet, let's hope it works). It has integrated GeForce 6100, which is fine for him right now. I noticed, however, that the pci express x16 only operates at x1. I was thinking about selling him my 8600GT when I finally decide to upgrade, but just how much is that x1 link width going to hold it back? I actually have 8600GT's in both of my pc's, one running at x16 and the other at x8 and I can really see no noticeable difference. Just how bad is it going to be at x1? And what card would you folks recommend for the best performance at x1? I appreciate any advice you can give me. Thanks a lot.