G'day Silvertones,
being an AD HOC setup there is no access point involved, there won't be a DHCP or DNS server involved either. This makes problems for stuff which the computer browser service should overcome. Problem is this service usually takes ages to update - not really helpful...

So, the easy way to alleviate this is to fix the addresses on the AD HOC network. Make the addresses from one of the ranges mentioned in my previous post (192.168.x.x, 172.17 to 21.x.x or 10.x.x.x - I suggest you use something from the 172 ranges to reduce the possibility of a conflict with any wired network you might connect to). Masks on both machines should match, addresses should be different but within the range defined by the mask. E.G. 172.18.1.1 and 172.18.1.2 with a mask of 255.255.255.248 (this will define a range of 172.18.1.0 to 172.18.1.7. Remember, the 0 and 7 are network and broadcast respectively so only 1 to 6 are available.

Then, you should be able to connect to the other machine by IP address rather than hoping the name will work (there's that slow browser service again). You can always update your local hosts files if you really want to use names. (C:\windows\system32\drivers\etc\hosts) Edit it with Notepad - the syntax has examples in the file. Make sure you end the last line with an <Enter> - this is important!

Also, in this kind of situation it is probably best to go into the TCPIP properties, Advanced button, WINS tab and make sure that either the "Default" or "Enable Netbios over TCP/IP" radio button is selected - if in doubt, select the "Enable..." option.

Get this going with your firewall disabled, then enable it to setup the additional security. Using encryption on the wireless is also a good idea, but again, get it going first then add the encryption - then if it stops working, at least you'll know where to look

--=-- My credo: If it's worth doing, it's worth overdoing - just ask my missus, she'll tell ya laugh --=--
You're only paranoid if you're wrong!