id say those are a tad bit warm for a 3.3GHz. Im o/c's to 3.2GHz with the Core 2 quad 9400. idle temps at 29-33c load 52c and im running on a heat sink with 4 heat pipes and a 90mm fan. 70 load is getting warm for you. the cooler you can get your rig the better. if its stable at those temps sure. but the cooler the better. you might want to look into some water cooling. it all depends on how long you want her to last. generally the hotter it is, the shorter the lifespan.
What is your Vcore set too if its on auto when you bumped up the bus speed it might be giving it too much which will cause your temps to be high. Now If you are on stock cooler then you should definitely get a better cooler if you plan on keeping it at 3.33GHZ your stock cooler just cant dissipate the extra heat.
Now IMO a good air cooler is just as good as a cheap liquid cooler If your looking for a good cooler tell us how much you have to spend and we will recommend the best for your budget.
Megahalems, Venomous-X, H50, Noctua NH-D14 are all premium coolers that'll come at premium prices, but they're sure to drop your temps.
I run the Prolimatech Megahalems with Dual YL D12SM-12 in push pull on my i7-860. I run at 3.8 with turbo and hyperthreading enabled. Idle temps are low 30s, average gaming load is high 40's, 8 hours of prime95 highest temp was 68.
The stock heatsink and fan units that ship with CPUs out of the box are adequate for running at stock speeds. They tend to waver a bit in performance when you overclock however which seems to the problem here. A decent aftermarket cooler should drop your CPU temps for you. You seem to have good case airflow at 28C so I'd definitely go for the cooler. Good luck!