The Lego Defender and Interceptor you are referring to is from the old Lego Star Wars Starfighter series, and do not fit in with the current (2010+) range, which are all slightly larger and much more detailed. I considered getting the old defender at one point, but it would just seem odd sitting next to the new ones.
Lego has updated the X Wing, TIE Fighter, Y Wing, Slave 1, Imperial Shuttle, Snowspeeder and just recently the A Wing.
I am working on a TIE Bomber design at the moment.