Power Supply?

Aswell as my new case (in previous topic), im wondering if i may need a new power supply. i think i have a 300watt one now (but how can i check this), wouldi need anything more (ie. 450watt) if i want to add a water cooling system and lighting,etc. to my athlon xp 2200, 512mb ram, geforce 4 4600, sb audigy? or wwill 300watt be sufficient for the water cooling etc.

Waterpumps are (more often than not) powered externally, for example:

The asetek waterchill Hydor L20 uses a hermaphrodite plug which goes into the back of your PSU, and the kettle lead from the wall plugs into the hermaphrodite. Meaning that no power is taken from the actual power supply.

Shop-bought pumps such as the Eheim 1046-1260 all have seperate wallplugs. Completely external of your powersupply.

Of course, you can buy pci relays that you use as a passthrough for your pump. these are used to turn on the pump when the computer is turned on, so you don't have to do it seperately. However, these will take little to no power from the psu, as it's just a relay.

The only additional outputs you'll really have to consider are the fan/s you put on the radiator.

A good 350W branded psu (Thermaltake, Enermax, CWT, Antec) would be absolutely fine for a watercooled system (as quite a few people might tell you). Although you might want to future proof your psu a little by getting a higher wattage job, taking into consideration future upgrades, etc