sony laptop loses connectivity with Linksys wireless routers

I have a Sony laptop model FS8900 (XP home SP2) that I bought a couple of years ago. It works fine at home wirelessly with my Netgear router (model SGR614) but it loses connectivity with Linksys wireless routers all the time. I use a WRT54G Linksys wireless router at a couple of locations & another Linksys wireless router at yet another location. I initially can connect wirelessly but seem to lose the wireless connection within a few minutes every time. I have not had any problems connecting wirelessly to routers of other brands.

I usually have to use an ethernet wire to connect to network at those locations. I have looked at Sony's & at Linksys' websites but have not been able to find a fix for the problem.

Any suggestions would be greatly appreciated.