How big of a difference do case fans make?

Right now I have a Vantec Aeroflow heatsink and 4 L1A Panaflos (24 cfm). Now, these things are so quiet, but I think my temps are a little hot. I can get over 50 c idle if there is no AC. Will getting more powerful case fans help this? I will definitely replace the TMD aeroflow fan, but I wanna know if its worth it to invest in different case fans too. What do you recommend (hsf and case) that push a lot of air and are [somewhat] quiet.

ive always been a fan of the smart fan II's and if ur looking for performance/quite the vantec stealth fans.

What size fans?
I have 2 - alum Evercool 120mm fans and I very rarely get over 112°F in a room that has ambitent temp of near 90°F ad about 75% humidity ( no air conditioning either )

80 mm

How good is the airflow in your case? I've got an Antec case with good airflow and spots for two exhaust fans and two intake fans. There is no temperature difference between using a single Stealth exhaust fan and using two 7-volted Stealths. I've also got two higher-speed fans that came with the case; running all four fans doesn't give any better performance than the single Stealth.