Well, When I talked to the owner of the Museum she said thanks for all the artifacts and gave me a belt. This was my first time there and I havn't sold one thing to her . Is this some weird glitch, also she's not letting me sell one of the artifacts of found that is really pissing me off .

Yes,for some reason many of the artifacts inside the book,she dosen't accept. I don't get it...

I don't know about why she gave you a belt. I do however know all of the items you can donate to the museum. They are:
Auriel's Bow
Auriel's Shield
BiPolar Blade
Bloodworm Helm
Boots of Blinding Speed
Boots of the Apostle
Bow of Shadows
Chrysamere
Cuirass of Saviors Hide
Dagger of Symmachus
Ebony Mail
Eleidon's War
Fang of Haynekhtnamet
Goldbrand
Lich's Robe
Iceblade of the Monarch
Lord's Mail
Mace of Molag Bal
Mace of Slurring
Ring of Phynaster
Skullcrusher
Spear of Bitter Mercy
Spellbreaker Shield
Staff of Hasedoki
Staff of Magnus
Ten Pace Boots
Umbra Sword
Vampiric Ring
Veloth's Judgement
Warlock's Ring

i given her all the artifacts that she will take and i was wonderin if it would be a good idea know to just slaughter every one in there? that way ill have a knew base of operations in mournhold and all my items back.

There are two of each of those artifacts. One is normal and the other has a script. If you find the normal one, she wont accept it because it doesnt have the right script (might not have one at all). So find the right one (if you can). Because i remember she wouldnt accept some of mine.

If you are questioning my knowledge, open the TESCS and check under Weapons.

Thats what I meant. If you laid the two out on the ground, the only way to find out would be to flip on the console and hold the cursor over the two swords. The one with the _x at the (end isnt it?) then thats your artifact to give her. You can keep the other for your self =o) IF you find both, that is...

what!! theres 2 of all these items? can anyone tell me where to find the second ones or give me a link? cause i got them all and i havent found any items with an _x at the end.

There aren't 2 of these items in the game without using the console... when you sell one to the museum, it disables the regular, _x-less one, and enables the other one with the _x on the end to replace it. It's for programming reasons.

Oh, ok Sorry, I was wrong. I was just going by the items int the CS.

I'm sorry to revive this topic but I have a question that has a lot to do with it:

Do you get anything for donating every possible item?

I didn't get anything. I have no idea what belt the original poster was talking about (unless it just 'appeared' in my inventory). You don't even get a journal entry closing the quest in the journal but then, in fact, you don't need to have the quest showing at all to sell her the items.

I have made a note on it in my pinned thread in Spoilers.