Slow network transfer speeds using windows XP

My Laptop transfers data on my wired network much slower than any other computer (which are desktops running Windows 98') in the workgroup.  For example, I clocked the transfer times for a folder 368 mb in size:

Desktop to Laptop - 33 mins
Desktop to Desktop - 2 mins

 After trying every solution I could think of (I won't list everything to keep this from becoming a novel)  I decided to do a clean install of Windows XP Home Ed.  After reinstalling windows my laptop's performance was exactly the same.  Does Windows XP have extra built in security (compared to Windows 98') that slows down file transfers over a network?  If so, is there any way around it?  Any other suggestions related to the problem or a resource for help would also be appreciated!

System Specs:

Laptop:
Dell Inspiron 8100
OS: Windows: XP Home Ed.
Processor: P III 1.13 Ghz
RAM: 256 MB SDRAM
Video Card: 16 MB DDR 4X AGP NVIDIA
Hard Disk: 30 GB (1.74 used)
Dynamic IP

Desktops:
HP Pavilion (3 stations)
Pentium III processor
OS: Windows 98 SE
RAM: 192 MB
Static IP

Switch and Router:
LinkSys Etherfast Cable DSL Firewall Router with 4-Port Switch VPN Endpoint
SMC EZ Switch 10/100