Another tip: Big capacitors (electrolytics) are notorious for failing after an amount of time or usage. The killer seems to be exposure to high temperatures.
Panasonic make capacitors that are specified to be more tolerant than most to this, and cost a little more - maybe 50p or so for big ones.
I always use them in DIY PSUs. Worth the investment. Think of it as insurance.
Also, if you site the capacitors well away from the hot regulators/ heatsinks, this is likely to extend the life of the capacitors. So will a cooling fan if the PSU gets really hot.
