I would get 2GB of ram. 2x1GB sticks. IMO it's a little unbalanced to have a GPU and CPU like that but only 1GB of ram.
What are you using it to do? If your gaming then I would definatly get 2GB of ram. I could tell a magor different in even 1GB to 1.5GB
(before i had a dual c. capable pc) while playing WoW or BF2.
Besides that the only thing i would change is get a 300GB 16MB cache, mainly for the double cache, and its not much more expensive.
Maxtor DiamondMax 10 300GB 3.5" Serial ATA150 Hard Drive - OEM at Newegg.com
or a little more expensive one that has SATA II
Maxtor DiamondMax 10 300GB 3.5" SATA 3.0Gb/s Hard Drive - OEM at Newegg.com
although there really isn't any noticble difference between 1 and 2 with what i read all the time.
I would at least definatly get the 2GB of ram, Even getting 2GB of DDR333 for 40$ each stick of 1GB off ebay would be better then 1GB of DDR400 IMO.(Mainly, it wouldn't increase the price, since you have a bujct of around 800$)