Hello! I'm really sorry if I'm posting this in the wrong place.
Anyway, I was wondering if I have to uninstall the base and expansions I have before installing the ultimate collection? Or does it just automatically install only the ones I need? I doubt it, but I just wanted to check.

You have to completely uninstall the base and expansions you have installed currently before you install the ultimate collection. People who haven't have run into problems.

Well that sucks. I assume uninstalling everything is a long and tedious process?

Not really. If what you have was all installed from discs, all you have to do is go into your control panel and uninstall all of the SPs, EPs, and the base game you have. If any of what you have you bought/installed through Origin, then you'll need to uninstall them through Origin. Shouldn't take long.

The longer/more tedious part is restoring your game to how it was, especially if you had things like camera mods and lighting mods and stuff that doesn't just get plopped into the Downloads folder. Some of those can be complex...but some of them are as easy as backing up your current camera and lighting folders along with your Downloads folder and your Neighborhoods folder. Either way, nothing to be afraid of. Some people have had trouble getting their neighborhoods and/or CC to show, but I think that's probably mostly user error. If you have a problem, look at the other threads that are littering this forum.

I read the help page about uninstalling TS2, and it says you need to do stuff with the registry or something? Is that not true?
I don't have any mods outside of my Downloads folder, so I'm not too worried about that.

I backed up everything in my Documents\EA Games\Sims 2\ folder, which includes downloads, hoods, some config files (startup cheats I think), camera mods, Body Shop projects, etc.

Then I dropped it in the new Docs\EA Games\TS2 UC folder (abbreviating because I'm on a tablet). Everything made it over intact.

Uninstalling shouldn't require registry editing. It's possible TS2 leaves some traces in the registry and that kind of thing can bug people, but it shouldn't prevent a reinstall.

Edit: it looks like that registry stuff is "worst case scenario" mode. Just uninstall from Control Panel. And remember that if you have your EA Games folder backed up somewhere safe, you're fine.

That is true to completely uninstall the expansions. Uninstalling through the control panel can leave bits behind and going into the registry and removing the bits left over insures that the expansions are completely uninstalled.

Thanks for taking the time to write this, on your tablet no less.
What do you mean by "bug people"? Like, what happens that bugs people?

Thanks for your help.
Could I just uninstall using the control panel and use CCleaner for the rest, or would I have to go into some sort of registry myself? I'm not very tech savvy and I'm sure that I would mess something up.

Can I install UC and just play the game still with my own cds? Or would I have to un-install the UC to keep playing with my own game?

CCleaner does gets the left over bits in the registry so its good idea to use the CCleaner if you're not comfortable editing the registry.

Well, some programs are bad about being tidy when they uninstall. They leave references, or keys, in the registry. These may or may not cause problems, usually not, but some people don't like them because it's untidy. If something isn't causing me any problems, I have a fairly laissez-faire attitude about it. But I'm also comfortable reinstalling Windows as needed, so I can afford to be chill.

To answer my own question: Having installed the UC WILL not allow to play your own cd game. And then you will un-install the UC. Which continues causing problems and suggests you re-install your cds. Which you begrudgingly start to, only to realize that the codes are currently at your parents' house on the other side of the country. So you might as well be stuck playing with the UC.

I have a question, if I may: Why one would want to uninstall the game, its EPs and SPs and re-install it through Origin and under the name of UC?

The current version(s) of the game will soon be unsupported. This means if anything goes wrong EA can say "Too bad" and move on. If you have the UC and it fries your computer, you might have a case. It's also a way of getting content you might not have been able to when it was still available retail. Also, 'cause Nostalgia.

In fairness, EA have been saying "too bad" if your TS2 game goes wrong since about a week after it was released.

Thanks, Kattenijin.

The game has been supported by modders and the community for the most part..
It is more likely UC to fry my computer than the physical discs I have already had, since both Origin and SuckaROM will interfere heavily in what it is going on with my PC.
I have bought all EPs and SPs except two SPs, which I didn't care to get upon their release, neither do I care to get now.

In my opinion, the truth is that EA tries to make everyone to jump into Origin wagon - and it seems to work splendidly. Good for them.