Jessica, there is special tri clothing that can go through an entire race. I recommend trisports.com for good selection and service (disclaimer: the owners are friends of mine). This is a good time of year for the end of season discounts. It is really really important to get clothes that can deal with extreme moisture, because, well, you are wet for lots of the race and chafing can be an issue. Load up on Bodyglide too while you're at it. For my last race, where none of my clothes are really fitting me, I swam in two water friendly sports bras, and tri shorts, threw on a jersey in T1, and wore all that out on the bike and run. I'll do the same this weekend.
I haven't found a knee brace or wrap style that is working for me. Today's issue seems to be a tendency to hyperextend (ouch) rather than a runner's knee or IT band thing, so as long as I'm paying attention with active muscular support, no worries. We'll see what new surprise there is tomorrow.
Anne


I hadn't been in a pool to swim since way before high school, but I'm feeling much better about it now. 
Hopefully I'll be okay to run tomorrow morning.