do the rear of these have a white bare outlining the tritium or not.  It seeme like I read advertisements talking about a white outline on the rear sight too.

Mine did, but that was a couple years ago, and I've since ditched those sights.  I still have some on a 1911, and they also have a white bar around the tritium.

How would I know whether im buying the ones with or without the rear outline

I would definitely want the rear outline

As far as I know, they only come with the white bar in back, regardless of whether you get a tritium rear.  I don't think they make a rear with tritium without a white bar around it.  

If you go with a tritium rear, your only real choice is whether you go with the standard size front or the "Big Dot" front.  I shot with these sights for about a year, and I went back to Heinies, as I felt they sacrificed accuracy at 25 yards.  However, I like them up close.  I also prefer the standard front, as opposed to the "Big Dot".  

Order the 24/7, and it will have the white outline rear with tritium.  You can order from XS, or you can order from a number of vendors.  Here is a link to Brownells.

www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=16797&title=SEMI-AUTO+24%2f7+BIG+DOT+TRITIUM+EXPRESS+SIGHT+SET

http://xssights.com/store/handgun.html