Would it really make a difference to have a DNS caching server for home? I saw a free program that I could intall on a PC to do it, but I didn't know if it would really make a difference.
If you have a broadband WAN link (128 Kbps and above), I don't think it'll make any difference. DNS queries and replies relatively form a very small portion of the total traffic when compared to interactive websites, images, sound and video. Besides as Kajitora said, the hosts/PCs them selves have internal caches for DNS queries. Talking windows, you can view the PCs cache using
ipconfig /displaydns
I have to say that it could make a difference however in the odd case were your ISP or public DNS server is slow (or is far a way, in the sense that pinging it would take long to reply).