You're probably between a medium and a Large. If you like long cockpits and a longer Wheelbase, go with the large. If you prefer shorter cockpits and a shorter wheelbase, go with the medium. Best way to decide is to demo both (on a trail!!!!).
Just to give you an example. I am 5'7" and everybody was pushing me towards a small. I went to a cannondale bike demo and the small seemed to fit fine, but as soon as I jumped on the medium, I knew I was home. A parking lot demo never would have helped me figure that one out. Now the only problem is money!!! Good luck!
I'm also 1.80m and ride a medium Prophet (also a 05 2000, sweet bike!). I could probably ride a large but on a bike like that, I prefer a shorter cockpit than a stretched out XC race position. It still climbs like a goat. But forget what I like, nobody can decide for you, try one, sit on one in a shop at the very least. If you really can't, compare the horizontal top tube length with your old/current bike.
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!