Start with a shuttle an35n-ultra (refurbished $38, new about $58) with a retail boxed barton 2500 ($80). For memory, any name brand pc2700 or pc3200 (crucial, micron, samsung, corsair, pny, mushkin) will work fine. You can start out with one 256 meg stick, and add another one later if money is tight. All prices from newegg.com.