Figure $1000 for wheels, tires, a new 105 groupset .... stuff like bar tap ... is your bike worth that to you? Do you really think it would gain that much?

I am with [MENTION=483845]Brocephus[/MENTION] ... why upgrade the C'dale? What's it lacking? A serious remake might be half the price of a totally new and much better ride .... or you could poach parts off EBay and make it a 10-speed giant-killer on the cheap.

As for RSX, check out this thread--http://forums.roadbikereview.com/components-wrenching/history-shimano-rsx-components-210389.html

If you have a good 8-speed bike now .... You could upgrade it to Hollowtech II and 4700 easily. Throw on a CF fork if it doesn't have one. Or you could just have a good 8-speed bike and buy something newer, lighter ... maybe rides better, maybe not.

Does the RXS stuff no longer work? For $250 throw some Vuelta wheels on there, $75 for lightweight high-thread-count tires .... and it will still be basically the same bike ... unless the bike just plain sucks ... but I would think that would be a nice frame to keep and work with. Since it has 130-mm dropouts you can run any road running gear from the last 30 years. Cannondale didn't make a lot of crap frames, as I recall.