I'm building a computer for a friend, its gonna have xp processor somewhere around 2000+, one hd and probably one cdrom, a ti4200, and an nforce2 mobo, and 512 ddr266 or 333. I belive 300 watts is enough, am i correct in this assumption?
I disagree. I'd say it would depend on the case. If it's a cheap one, they may be using a cheap power supply that's rated to supply 300Watts on an individual output rail as opposed to a 300Watt aggregate rating (when all output rails are being used - like what happens in a computer). Read all about it in this interesting "little" article here:
Actually at the AMD website the XP processors power supply requirements are for a 300W minimum, thats why a lot of people run into trouble, and adding a TI-4200, extra cooling fans, highgrade CPU cooling, and things like 7200RPM hardrives need more power, than the minimum requirements, its a lot better to have more than not enough, shoot for the 400W range and you'll be fine.
Details, Details, Its all in the Details, If you need help, Don't leave out the Details.
i'm sorry that's simply not true. a brand name power supply (antec, enermax, pc power and cooling) is a MUCH better idea than just any old thing. First of all check out the power supply review that THG did, and you'll see that all power supplies are not created equal. THEN think about the fact that if your power supply dies, it could create a surge and send entirely too much energy throughout your system and fry EVERYTHING (i've seen this in posts =(. So you don't want a crappy power supply. Plus a no name 300W power supply may not even provide 300W like it says it does (see THG review, again). Get a good power supply from the beginning and save yourself the worries!