Question : network two computers using ethernet crossover cable

I have a desktop running XP and a laptop running Vista. Using a crossover cable I managed to get them hooked up and talking but then used the ethernet adapter to connect to a router and when I switched back to using it to link to the laptop I couldn't get it to work.  The XP "repair" function didn't work because it could not renew the IP ("unable to contact your DHCP server). Having tried a couple of fixes I am now getting a different message : "the RPC server is unavailable". Using Control Panel/Admin Tools/Services shows RpcSs as "started" with startup type as "automatic" (all buttons greyed out). Please help!

Answer : network two computers using ethernet crossover cable

This most likely means that you had DHCP turned on in the router AND you have the network interfaces on the computers set to "Get IP Address Automatically" meaning that it expects to find a DHCP server connected.  But, it doesn't now that the router has been removed.

For such a small network I recommend this:

Set the IP, mask, gateway and DNS servers manually on both computers.

Let's say the router will be 192.168.1.1, 255.255.255.0 which is most typical.
Then the computers will be 192.168.1.xxx with subnet mask of 255.255.255.0
The gateway will be 192.168.1.1 whether it's there or not.  This just means that addresses outside the LAN can't be reached - which they can't of course - unless the router is actually there.

So, one computer might be 192.168.1.2 and the other 192.168.1.3
and, if the router is 192.168.0.1 then they'd be 192.168.0.2 and 192.168.0.3 instead.
See the common parts?

OK - now you need to set up DNS if you're going to connect to other worlds.
I typically use my ISPs DNS server IP addresses.
You can learn these from your ISP website usually.
I'd put in at least two.  Sometimes that's all there are anyway.

With these settings, the computers can talk to each other any time AND will work when set up with the router.