Careful about using longer cables. They can really cause problems. I have a couple of 1m long cables. They can be error prone at times.
Oh..I hate to sound dumb, but is it a normal 3.5" cable or a pokey little 2.5" one.
As for power supplies. Definitely go for AT/ATX. My A500 PS started complaining within hours of running the A500, 3.5"hdd and CD-ROM.
