Personally, on any system:
I would go with OSR and Streamline as a default, and only add the 4gb patch on a 64-bit system.
I would leave the 3gb switch alone. In my experience, and numerous comments from others; it may cause problems, and seems to add little or nothing in the way of improvement.

Yes. The "4gb patch" is pointless, if you are running 32-bit Windows. The other enhancements are not, regardless.

I suggest making sure that your next PC/upgrade includes 64-bit Windows. Probably Win8, by the looks of things...

Yes, it is. It may reduce CTD's, but it's only masking the problem. 99% of the time the game will crash for a reason. If you suppress these crashes then BadThings? can tend to happen.

He already has the option of a 64 bit OS with Windows 7, unless he was foolish enough to accept a computer that didn't come with an OS install disk. You should always insist on having one of those in case you run into problems and need to reinstall Windows. Otherwise you're at the mercy of your vendor anytime if there's an issue, and will have to hand over a bunch of money to them in order to fix it. If the store you're buying your gear from isn't willing to give you an install disk, go somewhere else to buy your equipment.

None of the above. Using these on a 32 bit version of Windows is to invite memory conflicts with your system drivers and when those begin happening, the system will BSOD. That's not something you want to have happen regularly.

That problem was supposedly fixed after XP, though I've never actually put it to the test myself. It's certainly an issue for anyone trying it on XP though. I was getting all sorts of glitches occurring when I added the 3GB switch to my XP boot routine, even a few "blue screens of death".

Sorry but I'm reinstalling OB and forgot this detail:
On which file(s) do you actually have to apply the 4GB patch:

1. oblivion.exe ?
2. obse_loader.exe ?
3. both ??
4. any other ??

Thanks for a very brief answer.

Hey, long time no see

I only ever applied it to Oblivion.exe as that is the only file in task manager that grew. I have seen others apply it to OBSE_Loader.exe and some dlls but I do not know if that ever did anything.

Hey, yes indeed Peter! I hope you are well. Yeah I'm due for another round of OB, if only to discover that I have had enough of it (which I doubt)... I got Skyrim delivered today, but I'll wait a bit before I install it... people are [censored]ing about the GUI for the PC version... DarN is looking into it... Considering what he did for OB, I rather wait for his mod.

On topic: Thanks for your reply. OK so I patched the ob.exe only now. Let's see then... Cheers!!

Yeah, I am staying away from Skyrim for a few months, wait for all the patches to come out.

After applying the patch you can test to see if it works by running Oblivion in Window mode and have task manager open looking at memory usage on oblivion.exe. Force a bunch of clones in the game and watch the results. You should go up to at least 2.5GB. If you don't get over 1.8GB before crashing then it did not work. I remember one time I had to do it twice.

Good lick.