Tri suit or shorts and shirt???

Neither. Most wear cutoffs and T-shirts like this:

Hey, you're talking about a sport where you shamelessly sport spandex galore...no way to not look like an idiot!

Either way, skinsuit (one piece), or separates, wear what you're most comfortable with.

"Do most racers wear a one piece tri suit or separate tri shorts and jersey?"

Yes.

I ask, Bear, why stop there?  Go for broke, like "Retroman" (multiple-time finisher of IMLP) in his cut-off shorts, Chuck Taylors, and single-speed complete with Banana Seat!:

No, he's drafting retro man.

I was curious on my first tri too, but in light of the pictures posted in this thread, someone will always be dressed worse than you!  Go with what you are comfortable training in.  Nothing new on race days goes for clothing as well.  If you have the physique for a trisuit and the cash ... then why not go for it.  I prefer the two piece myself ... gives me more flexibility on what to wear rather than being tied into just the trisuit.

MikeTri37 - 2007-09-01 6:23 AM I'm glad you guys are having fun with this....now what do you wear during a race!!!!

serious answers are sometimes hard to come by - when it has to do with wardrobe issues, i've found

good luck on your race!

I just started using a 1-piece this summer and I love it. I am long in the torso and have a bit of a spare tire, but with the 1-piece I can lift my arms over my head (swimming) or lean over with my arms in front of me (biking) without fear of the top coming untucked.

In terms of looks, I have the Desoto power skinsuit that actually looks like a 2-piece from more than 3 feet away. Got it for about $55 new on ebay.

Wear whatever you've got, and wear it proudly! 

Advantages of a 1-piece:  no inadvertent belly-flash, less likely to sunburn your lower back, only one piece of equipment to keep track of (but wow if you lose it). 

Advantages of a 2-piece:  works over a wider proportion of bodies, easier to use the restroom.