I actually just built my own poker table and was going throught the same delema. I found a couple of sites that offered free plans but I found them all very vauge. I did find a site though that sells an instructional dvd on how to build a poker table. You might want to check it out.
the site is www.pokertabledvd.com I actually baught the dvd and it is very informative and indepth. This shows you in step by step and covers istalling the rail and everything.