Ive noticed when if im down they hit me pretty often. And myself i hit more often, if they are down. Now am i imagining things here, or is there indeed such an effect. Could be useful if fighting with undeveloped weapon skills.

There's definitely a huge damage modifier for hitting a knocked-down target. I can't say for certain about a to-hit modifier, but it does appear to be the case from what I've seen. In fact, I don't recall ever seeing either my character miss a downed NPC or an NPC miss my fallen character (a couple of specific Nords and Bosmers with warhammers suddenly come to mind, rather painfully).

Time to make a lifeforce.. err.. fatigue svcking hot female soon-to-be-vampiress character i guess!

How do you know my ex????

ST

Yes there is. I forget what the extra damage you do for being knocked down, but yeah try not to get knocked down, it's not fun at all.

I would not think that the chance to hit increases, but rather that the chance to dodge decreases if a character is on the ground.

Chance to Dodge = 1.25(Agility/5 + Luck/10) + Sanctuary Bonus

It might be that if you're on the ground the Agility and/or Luck used in this formula decreases or disappears.

i hate orcs with warhammers, one knocks you down, you get beaten to death by all his buddies