This computer, $199: http://www.walmart.com/catalog/produ...uct_id=8304655
This monitor, $90: http://www.newegg.com/Product/Produc...82E16824009140
Note--I have no idea if that computer is by any means good or durable, but it should handle the tasks you've mentioned with ease (but will have to upgrade to a dvd burner if you want that option).
The monitor--I know, it's a CRT, but you probably won't find a new LCD monitor for under $150--and if it's that cheap, I'd question it's quality--and no use in spending an equal amount of money on a monitor as on the computer--I'd sooner take a lower-quality monitor and build a better computer.
So, if it were me, I wouldn't buy that computer. And for the most part, you get what you pay for--I built a cheap-o rig not too long ago--maybe a couple years or so--and regretted it 'cause it had so many problems.
You're probably going to be hard-pressed to build a rig from components for $300 or even $350 with a monitor--and provided the headaches you might run into, I'd suggest just going prebuilt 'cause at least there's some sort of system-wide warranty, etc.