Triple to a double or compact

[nscrbug]

I have a 2007 Trek 2100 WSD that I had not ridden in a year because I bought a new bike last year. Well, long story short...I am in the process of trying to sell my newer bike and shop for another one. But in the meantime, I am back riding the Trek 2100. There is a good chance (especially if I can't find a new bike soon), that I may end up riding the Trek for the rest of this riding season. Aside from the fact that the Trek is a tad bit too large for me, it is also a 105 triple. I have nothing against triple cranks, but for some reason...this bike shifts like total crap. Yes, I have had the bike in numerous times for adjustments...and I get told the same story - "That's how triples are..they shift sloppy". I know that some of you riding triples, debate this...and I don't doubt that some of you have super-smooth shifting triples. BUT...my question is...if I were looking to swap out my triple for a double or a compact...what parts are involved? Naturally, I don't want to dump a ton of money into this older bike...but if I end up riding it for the season, I'd rather not have the triple on it. So what exactly is involved for this project? Of course, I know a crank and BB, and likely the front derailleur...anything else that I'm missing? Would I need different shifters? The rear derailleur is already Ultegra, and the cassette is a 10spd 12-25, so I think I'm good there. I would likely shop eBay, Craigslist, or classified sections of forums for used components. Thanks!

Linda