I have a small & old Presario 5070 (500 Mhz AMD K6) as NASLite server.
It had a Realtek 8139B network card. It was SLOW!!
I could not believe how slow. Sending data from a WinXP, network thruput was never over 20%, and lots of errors (~1.5%, reported by NASLite).
I almost dumped NASLite...
Then I found some info on internet about how slow an RTL 8139 could be.
I installed a DLink DFE530TX (version C-1, detected as VIA Rhine III by NASLite) and the world changed...WinXP network thruput jumped to ~65%, NASLite flies, etc.
For all those having performance problems, dump your Realteks (8x39) and get better network cards. Not expensive, as a matter of fact (DLink 530TX should be around US$ 10), but with VIA or other chipsets.
NASLite is an outstanding (& very clever) idea. It shines on SOHOs.
Best regards
XD