Yes. just like what pizza the hut said, you would be saving some money, or could get better graphics card if you build your own computer. If you read some articles or two about making computers you'll be good to go to make your own computers. Computer parts come with warranties so if it goes wrong you can always get a new one. (ex. www.newegg.com
allows you to return your order and get a new own if it isn't working 100% gurantee.)
If you want a gaming computer, i seriously think you should stay away from any graphic cards with 128mb ram or less. and also, we HAVE TO know what kind of 256mb graphics card it is. If it's a 9600 256mb, it would be like 100 times slower compared to x800 256mb. do you get it? if it's precustomized, you have to pay them for their work and they charge you extra on stuff you don't even know. it's a hidden fee.