I got a core 2 duo build (without monitor) for 390 after shipping and rebates. Then a monitor I could probably scrounge up. I think this is the route I am going to go.
I'm guessing your don't game alot.
Ahem, read my first post. For my grandmother, not me. My rig is quite a bit better than that lol.
AMD 64 3200 75$
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103031
Corsair Valueselect 1 Gb DDR2-667 65$
http://www.newegg.com/Product/Product.aspx?Item=N82E16820146580
Asus M2N-E Socket AM2 93$
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131022
EVGA 7300 GT 60$
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130026
Nec DVD-Burner 31$
http://www.newegg.com/Product/Product.aspx?Item=N82E16827152076
XClio 450BL 450 Watt 38$
http://www.newegg.com/Product/Product.aspx?Item=N82E16817189003
Rosewill Mouse(Actually not bad looking) 3$
http://www.newegg.com/Product/Product.aspx?Item=N82E16826193024
Scthye Keyboard(Also not bad) 4$
http://www.newegg.com/Product/Product.aspx?Item=N82E16823105205
Sceptre 17 inch LCD 8ms 145$
http://www.newegg.com/Product/Product.aspx?Item=N82E16824112004
Re-use old harddrive 40 Gbs should be enough 0$
Total 515$
It's a bit over but you can cut back on the mobo and the video card if you wanted.
Forgot a case!! So it would probaly come closer to 550 with the case. Choose one to your liking:
http://www.newegg.com/Store/Category.aspx?Category=9&name=Computer-Cases