cuting 5x5 sheet of plywood effecivly

Greetings:
I'm at the point where I'm starting to cut the plywood (5'x5' sheet of baltic birch) for my interior cabinets (counter top, face frames, etc.), and for the life of me I can't get a straight, accurate cut using a circular saw.
Yes, I used a straight edge fence and I still can't get a decent cut, and I am not comfortable trying to cut something that big on my table saw. So after doing some research I'm considering purchasing a systems that converts a circular saw into a track saw. In particular, the EZsmart track system is available from my local woodworking supply store and the reviews seem positive. My questions are:
1. What do others use to break down a 4x8 or 5x5 sheet of plywood and
2. Anybody any any experience with the the EZsmart of other track system?
Any advice is appreciated...
Stephen
I'm at the point where I'm starting to cut the plywood (5'x5' sheet of baltic birch) for my interior cabinets (counter top, face frames, etc.), and for the life of me I can't get a straight, accurate cut using a circular saw.

1. What do others use to break down a 4x8 or 5x5 sheet of plywood and
2. Anybody any any experience with the the EZsmart of other track system?
Any advice is appreciated...
Stephen