I've been on 5,000-8000 a day for years and doing well. Get your levels checked occasionally. Closer to 100 ng/ml levels give the best protection.Yup. But beware; too much vitamin D will build up and cause you other kinds of problems, so don't go crazy with the supplements. 1000-2000 IU/day is appropriate, whereas 5000 IU per day is probably excessive, at least over an extended period.
Of course the best way to get it is naturally, i.e. some sunshine every day now that the sun is high enough in the sky to make that happen. Winters at higher latitudes can make that almost impossible, especially for people with darker skin. My wife and I have been down here in FL since mid-January. We generally go for a 45-60 minute walk out in the sunshine every day, which I believe obviates the need for vitamin D supplements.
Walking in the sun is GREAT!!! Rock it, Rossum!