jabber, most of the mums i speak to said that introducing solids didn't make a speck of difference to sleep, but yes i still cling to the hope that that will make all the difference
i think the one thing that has really helped me, particularly with naps, but a little bit in the evening as well is paying attention to LO's tired signs. i've read it in quite a few different books now, i think in baby whisperer and dr sears, probably some other places as well. the key is that once they are 'telling' you they are tired, you need to put them to bed immediately. yawning is the obvious sign, but also staring into space, turning away from things, quietening down, burying into your chest, whinging, getting fussy, etc etc. you just have to learn what your LO does. i learned that you can't wait 10 minutes, you can't finish your cup of tea or have a shower, they need to be in bed that minute in order to have the easiest time in getting them to sleep.
anyway, i still miss the window of opportunity sometimes and have to pick up the pieces. but i think this is what really got LO and I into the business of naps - all a matter of timing.
anyway, there are still days when LO gives me tired signs all day, even after he's just woken up!