overkill for your needs. Go to the hot deals forums (fatwallet of slickdeals.net). Wait for a hot deal from dell (I got a 24" ultrasharp lcd and inspiron 530N for $550 together). The 530 can be found on my craigslist or ebay for like $250 Buy another gig of memory and get one of the hot deal $100 dollar video cards. Depending on your vid card read the forums and it's overclockability. This will play new games well let alone really old games like wc3. You might have to upgrade the powersupply (PSU) (use hot deals again). Rinse and repeat in 2.5 years. In 2.5 years you'll have a faster computer than the top of the line today. Monitors, Powersupplys, and Case last a lot longer if you want to spend more in those components. PSU should be enough to cover your needs but not overkill, eg., you're not going to run a dual monster video card power hungry setup with 4 harddrives so you don't need top-of-the-line.
These days you can't beat the Dell deals even if you build yourself. Best to just get one, pump more memory, videocard, possibly psu. Save the rest of the money on an upgrade 2.5+ years later. You get way more value for your buck this way since you're not paying the bleeding edge premium.