Two PCs on wireless network but Plusnet Assist sees them as separate systems

[#1]

I have a desktop PC running on Windows XP and a new laptop running on Windows 7, both connected via a wireless router.  Using Plusnet Assist, the desktop sees the laptop, but cannot "decide" what type of device it is and the laptop cannot "see" the desktop at all.  Both machines appear to be logged onto different host networks.  The main problem is that my printer is connected to the desktop, but although I have set up sharing, the laptop cannor find it.
I tried disconnecting both computers and setting them up from scratch, but nothing changed....Help!

[#2]

I am highly sceptical about Plusnet Assist's ability to provide any real assistance.
When it comes to Networking XP and 7 together

• The default network name for XP tends to be MSHOME whereas for 7 it is WORKGROUP.  One or other of these needs to be changed to match


• Windows 7 sharing settings tend to be off by default but can be switched on in 'Change advanced sharing settings' in 'Network and Sharing Center'.


• Windows 7 in particular has an aversion to computers with no account password set.  You may need to set account passwords on both computer to persuade them to cooperate.


• If your security software includes a firewall, don't assume that will co-operate until pushed

[#3]

Also you need to be using the same account names with the same passwords on the two machines.