Apparently, there are people who want this sort of thing (that I'm one of them was my first clue). Here are your OWB creatures HP-stomped (among other things).

Download link:
http://www.newvegasnexus.com/downloads/file.php?id=43945

Give it a try and let me know what you think. This is my first mod, so I need all the help I can get (and then some, I'm sure).

Why? Aside from Dead Money, it's the only part of New Vegas that's remotely challenging... Games are way too [censored] right now.

The nerfing OWB needs is to balance over-powering rewards, perks, perks from challenges and implants that further destroy the Mojave.

EDIT: http://newvegasnexus.com/downloads/file.php?id=43263 fares well in that regard.

I don't think creatures having more HP's makes the game more challenging so much as it makes it more annoying. Creatures just require more hits to kill, which turns fights into tiresome marathons. This occurs in vanilla OWB mostly at higher levels, when players generally have enough high-powered armor that even creatures with lots of HP's aren't going to pose much of a threat. So why should those creatures require more firepower to kill than your average Mojave creature? It just looks like completely different balancing standards were applied, which is silly. I also don't think that higher level characters should require more firepower to kill creatures. You should feel stronger when you gain levels, not weaker.

If you want more of a challenge, enter OWB at a lower level. This mod's changes are noticeably less significant at lower levels. The HP reductions are not as great and you won't encounter as much inferior opposition. Or just don't use the mod. :\

Looking over the description of that OWB overhaul mod, I don't see anything that would conflict with this mod. Both could be used if you want to nerf both the creatures and the rewards. This mod further nerfs rewards by cutting down on the amount of high-value weapons you can recover from NPC's, a change the overhaul mod does not appear to make.