Don't have it? Darn.
They really don't make any major changes to the story as the story was never really that concrete in the games anyway (no real plot building opening, you just go BOOM right into the game). I think the man difference is in historical mode play. I never really noticed the difference though, it may have to do with who can join you and when or possibly ruler stats. The only major change if you pick Liu Bei or Sun Quan/Ce is really just in the challange. They control so little territory so it's a great uphill battle. But they're fun to pick if for no other reason than having Guan Yu
You more or less choose a ruler and as I like to think of it, have a chance to change history through your campaign. But since the game is totally different every time you play it there's really no concrete linear storyline (after all, you can win with Liu Bei
)
If you think 4 is tough, 8 is even worse
You have even more aspects added into the game including the ability to marry, etc.
Also, did you see the TV series? I never saw it yet, everyone tells me it's excellent and I keep meaning to buy the DVDs but money is always an issue
Maybe in another month or two.
If you interested in more Sanguo stuff you might want to check out
http://www.sanguo-online.com/ They have an online store where you can buy some Sanguo games at very good prices, lots of guides for the games, and FTP's with some of the older Sanguo games. I used to visit the page a lot. Only recently haven't been going as much.
My big gripe with RTK games is how high Cao Cao's War stats are. Cao Cao was no doubt the most sucessful man of the three kingdoms time going from a lower court official to controlling half the country, but he was a real wimp in terms of fighting. His politics, intellect, etc are all pretty good but that war stat is just cranked way too high.
Edit: A few last min additions. As far as the micromanaging, it's not that bad compared to some games. But it's really the biggest part of the game so you get used to it pretty quick. Generally the game strategy works for all the characters, you just need to spend a bit more time developing your territory with some of the toguher people. Koei has this big flaw that in almost all their games as long as you build up your first province really high, you can just roll out like thunder and crush everyone else on the map. Like in Gemfire and Nobunaga if you have two provinces and just buld them up huge, you can roll out and smash everyone. The reson is frontline provinces tha tborder you tend to have mass quantities of soldiers, reserves, etc, while all the inner provinces of the territory have virtually no troops, poorer management, less food, etc. So once you crush the front lines of a terrirtory you can drive in and divide and conquer. The challange with the tougher RTK games, Genghis Khan, etc, is not getting yourself killed int he first few years while building up.
After you've beaten the game once or twice you'll see your advisors really suck and can develop better strategies yourself