Question : how do i reconcile IP address conflict Between 2 PCs

Hi
I have trouble connecting my 2 PCs to my home network. One will connect but not the other & vise Versa. I think it might be an IP address conflict but thats a guess I have a Laptop downstairs with the hub wired to it. No Problems with that. I Have tried leaving the firewall open on both PCs but that has'nt helped. after about 5 mins one of them dropped again. Sometimes they both drop out, then only a reboot of the machine will bring the line back. Yesterday I uninstalled the BT software on the laptop, & reinstalled it all again without any effect. I Have XBox 360 Downstairs also, can only connect to internet over ethernet wire, Can't get it to work with WiFi, Have Got 2 Broadband routers spare but don't know how to connect them to the network to use XBox. Before Hub Arrived Used Buffalo Modem Router No Problems.
Thanks H

Answer : how do i reconcile IP address conflict Between 2 PCs

Have you re-booted/re-started everything? Sometimes after an update is made a good solid restart (router, pc's ... etc) makes a big difference.

Is it just the Vista machine now thats not connecting? Everything else online?