Shouldn't be too hard to change it out. It'll run you the cost of a new BB ($30-50) and appropriate tools if you don't have them. OTOH, I don't see a reason to change it out until it needs service or replacing. Another option is to have the store you're buying it from change it out as part of the purchase price.
After taking a look at the crankset on that bike, I'm not positive it'll be a simple swap. The crankset if made by Fuji and I can't tell if it's for a square taper, ISIS or something else. It's probably square taper, though, since it's listed as "Semi Cartridge Bearing ST" (assuming the ST means Square Taper) so this would be an easy switch. If not, the worst case scenario would be that you would need a new crankset along with a new BB. If this is the case, I'd recommend riding until you have problems and then upgrade. Should be able to get at least several thousand miles out of it before you have any problems. Like I said, though, probably square taper and easy to switch.