Considering your computer needs, you don’t need a computer with a lot of extras. You can get by with a basic computer without a lot of bells and whistles. Here are some you may choose from.
2.) http://www.officedepot.com/a/products/537939/HP-Pavilion-p6232p-b-Desktop-Computer/
3.) http://www.officemax.com/technology/computers/desktop-computers/product-prod2550290
In light of these links posted, my recommendation would be to simply just upgrade your existing computer. With a few upgrades, your computer would be every bit as good as buying a new computer, meeting all you needs and requirements, without paying the price. And if you look to these sites, most computers do not even come with a monitor, so it is something you have to purchase separately, thus increasing your “buying a new computer” expense.