Do you need a monitor? That would be a big chunk of change right there. I'm going with the assumption that you don't. I'm also assuming you won't be doing much overclocking.
All prices are taken from Newegg.com, one of the most reliable retailers out there.
~ $110 Epox 8RDA+ mobo (always get a good mobo evenifyou skimp elsewhere)
$67 AMD XP 1800+ Tbred RETAIL (no need for an expensive HS/fan if you aren't OC'ing just use the AMD supplied stuff)
$68 (2) 256MB Crucial PC2100 DDR (don't buy one 512MB stick you want two of the same brand/speed/size)
$145 Cardexpert GeForce4 Ti4200 128MB
$71 Western Digital 40GB 7200rpm EIDE hard drive
$90 Antec Lan Boy case w/350w PS ($18 for S/H)
$68 Altec Lansing 251 5.1 Speakers ($10 for S/H)
$50 Lite-On 52x24x52 CDRW RETAIL (only $2 more than OEM, + $6 for S/H)
$33 M$ Multimedia keyboard and optical mouse (+$6 S/H)
$25 Rounded cables and an extra case fan (I prefer the YS Tech 3700rpm fan that Newegg has, only 37dba for 48.5 CFM's)
That comes to $767 including shipping and handling and you will have a rock solid system with plenty of options for upgrading later.