I have 7 fans, plus my cpu fan, two cd-roms and two harddrives running on my 300watt power supply. Should I be worried/concerned about getting a more powerful PS or is the power sucked by the fans insignificant?
300w should be okay. but just so you know, almost all fans have a power rating on them... either in watts or amps. amps x volts (12, in this case) = watts. so if your fan says "0.25A", it's using 3 watts. this way you can add up the power used by all yours fans and get an idea what % of your power is consumed by them.
but they are all using 12v power... and a power supply can only put out so much power for each voltage. you should check the label on your power supply and see how many amperes of 12 volt power it can put out.