If you plan ahead, know what you are doing, you can spend your ideal budget (in this case you were speaking of $1,500 to $2,000) and get a new, powerful computer capable of handling all your tasks and last for the next three years. Not only that, but if you know what you're looking for, you can have the technology that is still cutting edge three years from now.
One thing to remember when you are looking at systems pre-built and off-the-shelf from stores like Wal-Mart, Best Buy, Staples, and the rest. You are getting computer systems that are at least one generation old already. You're buying old tech by going this route.
Just as an example. One business here in town that called me recently just picked up several "new" computers from Wal-Mart for their office in January. Wal-Mart told them these were the best computers in the store, and were Dell desktops with a monitor included costing $890 each. They bought three of them. Two months later they were running so slow that they called me to find out why. Came to find out these Dells were running Core 2 Duo processors (now two generations behind the most recent platform from Intel) with 3 GB of RAM on a very bloated installation of Windows 7 Home Premium. For their office tasks, 3 GB of RAM was enough, but it was all being used by the extra pre-installed junk from Dell that we just went through and did a fresh clean install of Windows 7 on each computer. For the same amount of money I could have built them a system with MUCH higher quality parts (manufacturer warranties from 3 to 7 years compared to the Dell standard 1 year), much higher performance (quad-core AMD Phenom II processor), and the latest generation instead of something that was replaced nearly three years ago.
There is a thread on here discussed not too long ago that answers a lot of your questions, Custom_Grafx, including recommendations on design computer systems within a range of budgets. The link to the discussion is here:
http://www.signs101.com/forums/showthread.php?t=77757