Linksys problems - WRT54G V1 and WMP54G v1.1 (and WAP54G V1.1 and WET54G)

I am having problems getting a reliable connections to my WRT54G router.

The router is attached to the DSL modem in the downstairs bedroom. I am
trying to establish a connection from an upstairs bonus room. They can't be
more than 30 feet apart.

My IBM Thinkpad X40 with integrated 802.11g works flawlessly -- solid 54mbps
connection and full 1.2mpbs DSL speed.

Nothing else does. The list I have tried includes:

1) WAP54G in repeater mode -- no connection
2) WRE54G range extender -- finally connects with upgrade V3 firmware in the
WRT54G, but DHCP fails now
3) WET54G connects but is slow. Internet connection speed is under 300kbps,
sometimes under 200kbps and has frequent dropouts. Conection quality is
above 75%, usually above 90%
4) WMP54G v1.1 on two different machines will not connect at all and doesn't
see the router at all.

I don't get it. All the machines are literally on the same desk. The
laptop screams. The linksys equipped machines moan.

Any suggestions?

Tom