There are a litany of reasons why you might consider buying a gaming PC rather than rolling your own rig, including cost. Yes, many graphics cards have recently settled down closer to MSRP, but who knows if they will go back up again? On top of that, system memory is still trending on the high side (compared to a year or two ago). For the most part, pre-built systems have been somewhat sheltered from these volatile markets relative to the channel. That means the opportunity still exists to get into PC gaming at a reasonable price with a pre-built PC; Dell's Inspiron Gaming Desktop (5680) is a prime example. In fact, the Inspiron Gaming line has consistently represented one of the best values in PC gaming...
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips