chainrings matching up to crank arm?
Yeah, you should be fine just to replace the chainrings. Make sure you replace them with Shimano (road) kit that is compatible with your 9-speed setup and you'll be fine. 

Note that rings designed for a 10-speed setup will strictly speaking be incompatible, since the 10-speed chain is narrower than the 9-speed chain. I have been told that you should be able to get away with this mismatch, although it will be suboptimal.

As a side note though, I'm not at all sure that this change will make you faster. Sure, riding on the large ring going downhill might give you a little more "oomph" (5% tops) but would you likely lose that advantage because climbing would be that much harder? And how much time do you spend in top gear anyway?

I mean obviously the wisdom of this change is entirely your call, but if it were me I'd think hard before I'd part with my cash on this particular upgrade. For hard numbers as regards the gear ratios of what you have and what you're thinking of buying, check out Sheldon's Gear Calculator.