Well let's take a look.
Athlon T-bird 900Mhz OEM (Is this place even giving you a T-bird or just regular athlon?): 45 + 10 shipping = $55
ECS K7S5A mobo (I assume you don't have a athlon DDR mobo?): 62 + 5 shipping = $67
256MB Crucial PC2100 DDR RAM: $29.68 free shipping
Maxtor DiamondMax Plus 20 Gig 7200 rpm HD OEM: 76 + 8 shipping = $84
WinXP Home upgrade: $99 (Assuming you have either 98, 98SE, or ME CD still in your possession for the reinstall)
Total = 334.68
Now, that's assuming you still have a decent case w/ Athlon-approved Power Supply, a CD-ROM drive or burner, soundcard, and floppy that you can use again. Only thing you might really need is the case with athlon-approved PSU, and with a whole list here
to choose from I'm sure you can find a decent case/psu for another 55 bucks. You'd still be under 400 dollars.
All those parts I listed are also quality
parts from respected online vendors (which are probably better than what they'll stick you with);I didn't even choose the cheapest parts and the lowest prices
So, if you really want to pay them 200 dollars or more to put your PC together for you... that is your choice.
Btw, this is being moved to our off-topic forum here
. This forum is only for the dicussion of Jedi Knight 2 and related topics.