The 9800GT requires a minimun of a 400 watt power supply. The 450 watt unit you picked will work but you'll still be running it hard. Sort of like driving a car at 80mph everywhere you go even thou the car has a max speed of 90mph. It will work but it may not last long.
edit: i wouldnt say completely avoid "green" drives, but i heard that they sometimes lack performance to conserve energy. if you want something of the same price get
Thanks, I took those suggestions and since none of them are mandatory I left it up to the person I am building it for to decide (I probably will at the least replace the dvd drive and HDD). I did hear that about the green drives and I am glad you suggested it, and I hate skimping out on PSU's so I will probably get that OCZ.