I played around with xmit power (how much power in mW) to see if I could increase the range and signal strength.  I don't think this Linksys WRT54G's strength is the wireless, it seems to have poor signal quality and transfer rates all around.

I think part of the problem is also that there are several wireless networks around my house that could be interfering and the walls are thick here.

Anyaway, moving on now :)  The default is 28mW and I increased it to 50mW and things improved slightly but I still didn't feel the signal strength was consistent enough on my iPhone (then again it is the iPhone and the WiFi is not especially great on it to to begin with).

Then I cranked it up to 70mW and as some said, higher power levels actually decreased my signal strength and throughput.  I couldn't even ping the gateway most of the time, so I lowered the setting to 60mW.

I've found 60 to be a great choice.  I really think it's time to upgrade/change my router to one that is known to have a stronger signal in general.   I just don't feel that the wireless in the WRT54G is very strong to begin with.

I imagine if I find a better router that turning up the xmit power would do a lot more, but at any rate, there's always a certain power level you hit where the signal strength and quality actually gets worse.  The other issue to remember is that high power levels could reduce the life of the router by generating a lot more heat.

I've read people talking about using 200+ mW for distances over a number of kilometers, however I have no idea how true that is but I'd be interested to test that theory if I ever got the chance.  One thing for sure is that if you crank up the power that high you better have extra cooling such as an external fan or even a small 40MM fan inside the enclosure itself to cool things off.