Personally I would consider VPS hosting before dedicated as the bang for your buck is far, far, greater and you esentially have full controll over the virtual server. Additionally you have the power to gradually scale up your memory from a cheap VPS plan to a more expensive plan if your average load keeps increasing

I like

http://www.slicehost.com

excellent customer service and a great user community...i'm not getting endorsements here, they are just that awesome

No need to contract into a $100+ a month for dedicated when a $20 month to month VPS will do the job just fine, I have no idea what kind of plan your on right now or what kind of load your getting...but if your currently on a bargain basement shared plan the $20 slicehost VPS probably has....oh, an allocated memory cap atleast 10 times higher. And hey...if it ends up being not enough, its very easy to scale it up gradually

my .02