Bitch Bitch Rable Rable. enough of all your guys mongering.
If you are an experienced photog with film, I would not bother with the Nikon D40. or the simmilar Canon Rebel ones, You will find them limiting as many of the features are designed for affluent soccer moms.
If you are looking to get into digital, which you should since 35mm will be dead in less then 5 years (is it not already?) I would strongly urge you to stick with which ever brand you have gone with in the past so you don't need to buy all new lenses. It is not like one is way better then the other, one year Canon has the best the next year it is Nikon. I would be more then happy shooting either right now.
When it comes to picking out your first body there is no reason to break the bank. Find something cheap, used and refurbished are good places to start. Check Craigslist and ebay. I got a refurbished 30D for less then half of retail. I and many others are getting fine photos without 10+ Megapixles. If you plan on shooting skiing alot though one thing I would want is at least 5frames a second for sequences.
If you are going Nikon I would look for a used 200D, or even a 300D if they are starting to pop up for sale. Both are great cameras. If you are a canon type of person I would look for Used 30D's or 20D's even a 10D (I know freezed takes killer shots with his).
When it comes to lenses remember that most DSLRs use a size 'C' sensor. This will give you a 1.6 crop on all your photos so all of your lens will be 1.6x what they were on your film backs. This also means that it is slightly harder to hold a steady shot with Digital then with Film; making I.S. lenses more worthwhile.