Its good you are thinking ahead, but you didn't ask the right question. The sound system you described is just that... a SOUND system & the TV you described is a VIDEO unit. So really... you need to make sure whatever media device you use (dvd player or whatever) will be able to provide sound to the sound system & video to the video unit. I'd imagine that any basic dvd player will be able to provide video over a composite line (the single yellow RCA jack), but the real question is... does your DVD player have a digital output to provde a 5.1 surround sound signal to your new receiver? If it doesn't... then you would be forced to use the red/white stereo outputs & won't ever really have surround sound... but rather the same signal going to the front & back speaker on either side. The center channel would likely output either an average of the two or perhaps just the left signal. I don't know much about that specific receiver.
I'm thinking of buying an Onkyo Home Theatre system - the HT-S760. My question is whether my TV will be compatible with this system? I have an RCA ColorTrax Plus Stereo Monitor with left and right input and output RCA jacks and a video input jack. I'm a neophyte at home theatre and would appreciate any advise given. I do plan on upgrading my TV to a big screen in the future, but have been waiting for the plasmas to come down in price. Thanks in advance for your help.