I use the Linksys WRT54G, and it is great - no signal issues (a bit of moving the antennae, but thats all) and reliable.
It is simple to configure, and Even enabling 128bit WEP does not seem to effect the throughput greatly.
I have never personally used the D-Link kit, but I know a number of people who have (mainly work colleagues who call me for support

) and they appear to be pretty good as well.
From a personal perspective, Linksys is owned by Cisco, and the kit has had a number of modifications since they took over. I now look at linksys as cheap cisco kit