A well designed and synergistic selection of characters in 3.X just using the core PHB would probably win against those 8 ogres. It depends on some factors, but if things are going the PCs way based on some controllable factors (stealth, fighting outside, etc.), then I can see winning that fight without too much hurt on the party. I'd feel pretty good about fighting those 8 ogres with a level 4 human fighter or barbarian, human wizard or sorcerer, halfling rogue, and human druid.
Opening a room and finding 8 ogres? Well, you can keep them stuck fighting in the doorway. It's going to be a little tougher, but bottlenecking them will help a lot. If the Wizard uses a
Glitterdust spell, half the group might well be blind (DC 17 ish vs. their +1 to Will). A well aimed
Grease spell will incapacitate most of them (they get +0 Reflex, and it makes them able to be Sneak Attacked if they fail a DC 10 Balance check [they get -4]), and that means that the halfling rogue is going to be getting +2d6 Sneak Attack damage (hits on an 5+, which isn't too bad). Being blinded and flat-footed really hurts. The wizard can probably follow thing up with a well-placed Ghost Sound to mimic the party, perhaps getting blind ogres to attack one another. The druid can use a Spider Swarm to attack up to four ogres at once (if they're crowded together), each round dealing 1d6 plus poison (ogres only have about a 20% chance of failing a save, but it makes them make two saves, one of which nauseates them [means they can't attack]). With 8 saves at 20% being made per round, odds are alright that 1-2 saves will fail. Additionally, the druid can clog up the doorway with a Summon Nature's Ally I (which he can spontaneously convert to), tanking for the party by blocking the door (sure, it only lasts three rounds, but the blinded ogres miss 50% of the time, and have a 20% chance to be nauseated). The fighter can attack using his ranged weapon, and use his tower shield for full cover when the ogres finally get through (readying to 5-ft. step back and let another Summon Nature's Ally I take his place). The brunt of the assault will be within three rounds, but it's definitely doable. The party has used up substantial resources (probably half), but they're taking on a very tough challenge.
If the party is in the wilderness, casting the
Entangle spell (80 feet wide) will catch most of them (DC 15 ish vs +0 Reflex), keeping them rooted in place. The others will be lowered to half their normal speed, and the area will keep trying to entangle them each turn. Circling around the area to avoid escaping ogres or picking them off is possible. Hit and run tactics with spells and bows on horseback is also an option (trap them, pepper them, run around or away).
In either situation, with a well organized party, I think it's very doable. And this is just the core PHB. Throw in some more options, and the party can improve (I haven't factored for magic items, only masterwork weapons, as that's core PHB). Yes, it'd be tough to keep the pace up (well, for the room, at least... you could perform quite a few hit and run tactics against ogres for relatively minor resources), but a well oiled 3.X party will not be "obliterated" by 8 ogres. If ambushed, then yes, they're probably screwed. If it's an even fight, I give the adventurers a fair shot (ogre's get -1 initiative). If the adventurers are very careful and are picking and choosing their battles, then I give it to the adventurers.
Anyways, just thought I'd throw that out there. If you increased the party size of the 3e party to 7, I'd say it swings considerably in favor of the PCs. It just depends on party tactics (which, I think, was the point of some people this entire time). As always, play what you like
