I've set up ftp server on my Windows 7 Box (Filezilla). Download speed from this server to Windows 98 machine (Pentium 3 550Mhz, 3Com SOHO NIC, Total Commander ftp client) is about 7MB/s.
Is DMA transfer for HDD turned on ? I've noticed big differences in transfer after turning on DMA.
Scamp: 286@20 /4M /CL-GD5422 /CMI8330
Aries: 486DX33 /16M /TGUI9440 /GUS+ALS100+MT32PI
Triton: K6-3+@400 /64M /Rage Pro PCI /ES1370+YMF718
Seattle: P!!!750 /256M /MX440 /Vibra16s+SBLive!
Panther Point: 3470s /8G /GTX750Ti /HDA