what psu do i need

I am planning to build an athlon 2600xp in an m7ncd motherboard with 512 ddr ram,Someone suggested an antec sonata case which comes with 380w psu which is a lovely case but a bit out of my price range could any one help me with some advice on case and psu

You need at least a 350 watt psu for anything newly built, but I'd recomment more, like 430w or higher. Be sure to get a good brand (antec, enermax, zalman, thermaltake, etc), don't try to save a few bucks on the psu, cause if it goes it could take everything else with it.

thanx I will have a browse

Forgot you asked about case too. For a budget, I like the Chenbro X-pider. The Aspire X-dreamer is also a cool case for a good price, if you like the windows and such.

The important thing to remember is that a good quality 300w powersupply is a lot better than a cheap 'ol 430w PSU. Some common brands that are known for good PSUs are:

Enlight
Inwin
Supermicro
Skyhawk
Antec

With your specs a 300w should suffice, unless you plan on using a video card with another power connection on it, like ATI 9xxx video cards then maybe you should look for a 350w PSU.

300w isn't enough for a newer graphics card, and will limit upgradability.

Maybe you missed my last sentence.

Either way, a 430w PSU is overkill for a typical computer user, his money is better spent elsewhere.