It won't post..power supply seems good fan runs..hard drive spins up..no post or video signal..person never did clean out the inside alot of dust and crap on the heatsink..I figure it is either the mother board or cpu.. is it worth repairing or is there a way to test either of the 2..pc is around 6 years old..thanks for any help

I'd try unplugging everything from the motherboard and reseating.
Start with the CPU & memory -try booting.
If that works (single beep) ,video card next -reboot.
Add stuff till it quits booting or starts working.

E Machines installed some very flaky power supplies in some models of their computers in the past few years. These defective supplies damage the motherboards when they go bad. Do a Google search and see if your model is one of these. If it is, you likely need a new motherboard and a new power supply, so repairing it probably isn't worthwhile.

I also have an e-Machine, however it's 4 years old. It's my understanding now, is that E's components can be the cheaper stuff. I've had a few problems, software related, ..that's been straightened out. Recent advise I've been given is to .... plan ahead and build or buy a replacement, since 4 years with an e-Machine, ... puts me on borrowed time.