Have you tried changing the location of the access point in your house? If it is located near a large metal object that could interfere with radio wave propagation.
You can test for signal-to-noise ratio (SNR) using
Netstumbler, which should give you some idea about whether interference is a problem.
When you say you've tried switching channels, did you switch from 11 to 10, or did you switch from 11 to 1? If you are receiving interference from other wireless access points, then you have to move several channels in order to avoid it. Depending on the source of the interference, changing channels might not make a difference.
If you are getting interference on all channels with 802.11b/g, you could switch to 802.11a, which operates in the 5GHz band, far from the spectrum occupied by 802.11b/g.
HTH,
Zac