roaringlion510: The Ultima IV that is available as a stand-alone for free is indeed the same game available in the Ultima 4+5+6 pack, so it's a good way to get a taste of the series without really having to worry about investing anything except a little time.

The Ultima games play a little fast and loose with their canon (Ultima IX tends to get an awful rap, but it's not so terrible that it should be avoided at all costs, in my opinion, it's some good ideas with flawed execution when it comes down to it), but they're not so closely tied that they have to be played in order - I certainly didn't! Each of the games does a pretty good job of standing on its own, even as a part of a larger story, so while playing them in order does give you a better sense of 'continuity,' it's far from necessary, so it tends to be more a matter of figuring out which engine suits you best (each of the games used a new one, with the exception of the spinoffs).

In asking what the best one to start with is, it depends on what it is you're looking for - Ultimas 4 and 7 tend to be the usual recommendations. Ultimas 1-3 are very basic, simple 'go-kill-the-big-bad' stories that tend be rather grindy and can be frustrating until you hit upon that magic mix of familiarity with the system, skill, and luck - they generally can be passed over unless it's a matter of historical interest or how the series got its start (although I rather like Ultima 1 for its quirkyness, and Ultima 3 has grown on me in recent days).

Ultima 4 is where the series really took off, kicking off a somewhat more philosophical bent to the games' story, which continued through Ultima 5 and 6. If you're looking for a unique sort of narrative and don't mind a keyboard-input command system that can get a bit clunky sometimes, I'd suggest Ultima 4 as a starting point (it's also my personal favorite of the series). Ultima 5 improved on the interface a bit and added a few new mechanics, and Ultima 6 improved even further, and they've got good stories of their own. The Worlds of Ultima games (Savage Empire and Martian Dreams) use Ultima 6's engine, are also available for free, and are interesting games in their own right, so if Ultima 4's control scheme is a little grating on you, I'd suggest snagging one of those and see if that feels any better for you.

Then there's Ultima 7, continuing on to Serpent Isle in the same engine, and that's the other generally recommended starting point. It's a mouse-driven interface that feels rather more modern than the previous games, so if age tends to be a stumbling block for you, Ultima 7's your game to start with. Again, it's a good story, and it springboards off onto Serpent Isle, which tends to rank pretty highly among lists of favorite Ultimas (mine included, I enjoyed it a lot).

Finally, there's the Ultima Underworlds, which are tangentially related to the rest of the series (Underworld II moreso, it's set between Ultima 7 and Serpent Isle), and they're first-person dungeon crawlers, so if that's more your thing, pick 'em up.