Well having problem with the network speed on linux 7.3, i get 70% packed loss on the local network. at the same time this machine also
I have been using Realtek based NIC's RTL 8139 all my life and they have not given me any problems whatsoever. Dunno, but check if you have the 8139too.o module insmod'ed. Older Realtek 8139 cards used the rtl8139.o module. 8139too.o is the new avtaar of that old driver. Use this one and not the older one.
To be on the safer side, go to http://www.scyld.com and download the latest driver for that chipset.
-- ashok