Spend little, dont be a fool. I am thinking of a building a computer too.
My advice go with AMD, it is cheaper than intel. Dont get the newest cpu, instead look for a low priceerformance ratio, divide price by speed.
Video cards. You can easily be confused. My advice go with a nvidia 128 meg gforce 4 or 4mx. Yo could get a 256 meg card but it will cost you more and you wont see the performance.
Case. Go with a case/power-supply combo it is cheaper than buying individually.
Motherboards. There are lots so pick one yourself, I cant help you.
Hard drive. Hard drives are sold at places like Future Shop, at these big store you can get big rebates. The one in my city had 30 gig maxtor 7200 rpm for 39.99(canadian dollars) after all rebates. So maybe you should buy your Hard drive from somewhere like that. You dont need a big HD. Remember price:space ratio.
Ram is tricky. It is a common upgrade so it can be found at a big strore=rebates. Go with 256 megabytes of system ram.
Disc drive. Well its not really important. Any cd-rom should do. A new dvd technology is coming out(not sure when) called Blu-ray=higher capacity dvd discs. Oh and dont get a floppy drive, but if you do get a cheap one.
Monitor. Try to buy one used or get a new 17 inch monitor. Keyboard and mouse go cheap.
Operating system. Is up to you which you get and how you get it
Sound card. Unless you want surround, go cheap.
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For lower cpu and motherboard prices wait for the athlon64, which is to be released in september. Current cpu's will drop in value and then so will the motherboards. Don't buy an athlon64 until a version of windows is released that supports it. When that happens the athlon64 will go down in price due to increased sales, and so will the current stuff now.
At least wait for the althon64 this september to come out.
In Canada I could get a decent computer minus os for $500-$600cnd. Remember comuters go down in value fast, wait for a price plateau.