Network latency after switch from W2K Server to XP Pro

We made some recent changes and are having response problems. Changed from: Client/server with a P3 domain controller as server with 500Mb RAM and running W2K Server OS. Changed to: Peer-to-Peer by replacing the P3 with a dual Xeon, 2Gb RAM, mirrored SATA drives running XP Pro Sp2. It is dedicated and only operates as a file server. There are three workstations, all of which stayed the same. All have 1Gb RAM and run XP Pro SP2. The network stayed the same: Ethernet thru a 10/100 router and switch. There is minimal network activity. Only files from 2 applications are on the server. Here’s my response problem: Under the old configuration, when a workstation accessed the folder on the server (W2K) , we had instant response in displaying the folder contents. For example, a folder was accessed through a mapped drive, is about 40 Mb in size and holds 3000 portfolios. Content was displayed at the workstation with no delay. Under the new configuration, using exactly the same techniques, we get a long (sometimes 20 seconds) delay before the folder contents gets displayed. We see this delay in applications but this same delay is seen even when using Windows Explorer and browsing to the folder. The issue seems to be the number of files in the folder, not the size of the files. Windows Explorer will display 6 files totaling 30 Mb very quickly but 1000 files totaling 20 Mb displays only after a delay. When at the server keyboard, there is no delay when accessing these folders using Windows Explorer. Thinking it was the mapping, I changed all access to use UNC. No change. I did notice that I get almost instant response if I access the ‘share’ through ‘My Network Places’. That seems to use UNC. But if I take the exact UNC resolution shown in the address bar and try to get to it using ‘run’, I’m right back to the delay. I’ve worked with Dell (the server) and Microsoft. I’ve changed all the hardware, cables, and reloaded all the drivers. Everyone sees the problem but no one has a fix. Microsoft, at the highest support level, had me show it to them 3 times, put me on hold for 10 minutes and then told me ‘that’s how it works’. They were not able to explain why ‘My Network Places‘ gives me the response I want but nothing else does. Should I really expect worse response with XP than with W2K Server? Has anyone else seen this? Fixed this? Any suggestions appreciated…