Asus EAH 5750 Formula, overclocking, changing thermal paste?

I have mentioned graphic card, and was wondering if changing the thermal paste is realy worth it. I actually did it already but cant remember the stock thermal values under load. But Im wondering if it realy was even worth it, since the the thermal paste that come with the Formula cooler seemed to be pretty tightly in place. Thermal paste I placed on it is Arctic Cooling MX-4. And yes Im using the stock cooler since it was pretty good to begin with. I might have gotten the thermal values few C down but nothing big.

Question is, is changing thermal paste generally worth it or not? How about on those that are asus specific "cool" versions like my, is it realy worth it or not? Yes Im having second toughts here, thats why the topic.

Overclocking seems to get temps very high. And the memory I wont even recommend to overclock since they dont seem to have any heat sinks at all!! Seems that even small changes like 50MHz make the memory very unstable, while the GPU can be overclocked up to 850MHz while having it quite stable. However I keep GPU 800MHz since I believe it would be slightly stable and have lesser voltage strain on the GPU. Also what I have heard is that overclocking the card with CCC is not the most optimal solution since it might do the voltages wrong.

Info on the Graphic card:
http://www.overclockersclub.com/reviews/asus_eah5750_fo...
(tested those clocks mentioned in the topic, memory seems to go quite unstable with them)
http://www.lostcircuits.com/mambo//index.php?option=com...

-BlizzardGamer

Ps. Also, Im considering to buy new graphic card in timeline of somewhere around 6 months. Any good ones to suggest around 100-250 euros that would still be major upgrade technologically? Uber high fps Im missing out, but if there is card to suggest that would be technologically "way ahead", please do suggest one thank you.