Server2003 can't connect to the XP client?

Hello
I'm studying for the 70-290 exam, and therefore downloaded the evaluation version of Win Server 2003 R2 from microsoft.com. After installing it, I promoted it to a DC by running the configure your sever wizard from the "manage your server" page. I chose the "typical config for a first server" option.
So it installed the DHCP service, Active directory and created a domain called "contoso.coml" <- the l was a typo, but it really does not matter either way anyway.
After that I connected this computer and another computer that was running XP SP2 in a network, using a 4-ports hub. And then I joined the domain with the XP SP2 computer, and everything seemed fine, until I tried to remote control the XP SP2 computer from the win 2003 computer.
The thing is that I can ping the server from the client computer, and I can also connect to it, but I can't ping the client computer from the server, nor can I connect to it. I have not activated the evaluation version yet, but I dont think that should be a problem, because it should run with all features for 14 days.
Anyway, the client computer was receiving ip from the DHCP service, so I tried to give it a static ip, but the problem remained. Does anyone know what could be causing the problem?
All input would be appreciated.
PS Please excuse my poor english.
I'm studying for the 70-290 exam, and therefore downloaded the evaluation version of Win Server 2003 R2 from microsoft.com. After installing it, I promoted it to a DC by running the configure your sever wizard from the "manage your server" page. I chose the "typical config for a first server" option.
So it installed the DHCP service, Active directory and created a domain called "contoso.coml" <- the l was a typo, but it really does not matter either way anyway.
After that I connected this computer and another computer that was running XP SP2 in a network, using a 4-ports hub. And then I joined the domain with the XP SP2 computer, and everything seemed fine, until I tried to remote control the XP SP2 computer from the win 2003 computer.
The thing is that I can ping the server from the client computer, and I can also connect to it, but I can't ping the client computer from the server, nor can I connect to it. I have not activated the evaluation version yet, but I dont think that should be a problem, because it should run with all features for 14 days.
Anyway, the client computer was receiving ip from the DHCP service, so I tried to give it a static ip, but the problem remained. Does anyone know what could be causing the problem?
All input would be appreciated.

PS Please excuse my poor english.
Current certs: MCP (210) MCSA (270, 290, 291 and 680) MCTS (680, 640)
Comments
You might want to deactivate the firewall at this point to enable full communication between the xp and 2003 comps. Also, have you check if remote desktop is enabled ?
__________________________________________________________
MCP (282 - 270 - 284 - 290 - 291 - 293 - 294 - 298 - 299 - 350)
MCTS (351 - 620 - 622 - 647 - 649 - 671)
MCSA / S / M - MCSE / S
MCITP (EST - EA ) - MCT
A+ - IBM - SBSS2K3 - CISCO_SMB
CompTIA : A+
What do we win ?
__________________________________________________________
MCP (282 - 270 - 284 - 290 - 291 - 293 - 294 - 298 - 299 - 350)
MCTS (351 - 620 - 622 - 647 - 649 - 671)
MCSA / S / M - MCSE / S
MCITP (EST - EA ) - MCT
A+ - IBM - SBSS2K3 - CISCO_SMB
CompTIA : A+
Ps the weird thing was that I could not even ping the Xp computer, but it did receive ip adress from the DHCP service of the Server 2003 computer.
The XP firewall allows all outgoing traffic (and the return traffic) by default. It only blocks unsolicited inbound traffic. So pinging from the XP client or a DHCP discover from the client will work just fine with the firewall on.
We win smilies.