You don't need an a520 with an A1000. A1000 has color video out (which is what I would use) and it also has an RF modulator built in (need a c64 style large din type cable I think) if you have a really old tv that had no video in.
A1000 video out is really really good quality. If I remeber the A500s/A2000s video out was B/W(why? why? why? 4096 colors in B/W?? Grrr!!! Comodore) so you need the a520 which is garbage if you ask me. If you are using it for games and things this is my preferred method anyway. If you use an RGB monitor games don't look as good as you see all the pixels.
...
Good point. Using composite monitor is like having a free interpolator built-in to smoothen the pixels (for low-res). RGB monitor is better for higher resolutions. Why they put B&W composite in A500/A2000-- I guess to try to make it cheaper. But A520 is decent for most uses. You can always use SuperGen's (or some other good genlock's) composite/svideo outputs if you need the higher quality.