Yup, it should work just fine. So should this one:
<a href="http://www.dpbolvw.net/3t121kjspjr69FGB79D687BB7FGE?sid=Newegg+Affiliate& url=http%3A%2F%2Fwww.newegg.com%2FProduct%2FProduc t.aspx%3FItem%3DN82E16833156139%26nm_mc%3DAFC-C8Junction%26cm_mmc%3DAFC-C8Junction-_-Network%2B-%2BInterface%2BCards-_-Trendnet-_-33156139&cjsku=N82E16833156139" target="_blank" onmouseover="window.status='http://www.newegg.com';return true;" onmouseout="window.status=' ';return true;">
TRENDnet TEG-PCITXR PCI Copper Gigabit Network Adapter</a>
<img src="http://www.awltovhc.com/55108ax0pvtEHNOJFHLEGFJJFNOM" width="1" height="1" border="0"/>
or this one:
<a href="http://shop4.outpost.com/product/3887837?site=sr:SEARCH:MAIN_RSLT_PG">Link</a>
(I've used several of these... They go on sale at Fry's (in store) for about $5.00...)
or this one if you don't need gigabit (it's a 10/100 RTL8139):
<a href="http://shop4.outpost.com/product/4278294?site=sr:SEARCH:MAIN_RSLT_PG">Link</a>
(this one is on sale <b>in store</b> for $2.00)
The RTL8169 will be supported natively (there's already a "driver" in 10.5.1 and 10.5.2 for the RTL8169 AND the RTL8139) so you shouldn't have to install anything else.