The system temperature is dependent on the temperature of the room the computer is in, along with the airflow of your case. 33C isn't anything to worry about, although a lower case temperature means cooler air blowing on the CPU heatsink; but 33C really isn't going to make your CPU any hotter. As long as your CPU is maintaining a good temperature, don't worry about the case temperature too much.
Your chipset doesn't need a heatsink with a fan. SiS chipsets don't get very hot, and even the faster chipsets from VIA or nvidia don't need a fan, as a large heatsink is plenty to cool them (and the SiS735 is fine with the small ECS heatsink). Fans are just a gimmick so that board makers can make more sales to people who think they need "extreme cooling". Only if you're overclocking a whole lot will the chipset get any warmer than a heatsink can handle.