Does anyone have a XP MCE networked to a Vista system?

[carlgar]

I would like to know if anyone has a Windows XP MCE edition networked to a Vista OS and working properly.
I just became aware of a strange networking issue between those 2 Operating Systems. The networking appears to be working properly until I need more than 2.5% of my 100 Mbps NIC on the XP MCE OS. The transfer appears to be limited to about 2.6% of the network utilization.
I have 3 systems available to me, they are:
Server - running Vista XP Home Premium with a 1 GB NIC, primary use is Sage Server.
Laptop - running XP MCE with a 100 Mbps NIC, runs Sage Client and PS.
Backup - running XP with a 100 Mbps NIC, has Sage Client and PS, very seldom used.

The Backup system does network transfers between both the Server and Laptop properly. But the Laptop will not transfer to or from the Server with decent speed. I have even tried to use the wireless NIC on the Laptop and it also appears to be limited to an even slower speed. At this point it looks like a problem with the XP MCE system comminucating to the Vista system. I know that it worked properly at one time after I updated Vista to the SP1 level. The laptop is now updated to the SP3 level but I saw this problem before that. Does anyone have a XP MCE system networked to a VISTA system and working properly?