Swapping out parts is a *lot* easier than most people think. I just opened up my case and started, with no training, and learned by doing.

I'm not saying that an A+ course is a waste, it can save you a lot of learning time, but a computer's nothing like a car where the insides are so unbelievably complicated that only an engineer can make sense of it.

To change a video card, you simply remove the one screw holding it in place, pull up to remove it, and insert the new card in the same place and secure it with the same screw. Same deal with a hard drive, except there's usually four screws holding it in place, and you *sometimes* have to remember that the red line on the cable from the HD to the mainboard should be facing pin one--but then again, most HDs/cables these days are keyed so that they cannot be inserted backwards (A notch on the cable must match a slot on the HDD, otherwise you won't be able to insert the cable)

Nevertheless, until you get some hands-on experience working inside a computer, I'd still reccomend going with a prepackaged deal such as Dell--You can learn bit by bit, upgrading single pieces of hardware in an existing computer fairly easily--if you just buy a box of parts and try to assemble it with no previous experience, you really won't have any way of figuring out which component is causing you trouble when problems happen--and they will, even for experienced techs.