If you are reaaaaalllly going to get into photography, then you will definitely want to heed Mr. Ambassador's advice. However, you really need to consider if the extra weight, bulk and cost is worth it to you. Clearly it is to Mr. Ambassador, but it is not for everyone. I used to shoot a lot of 35mm film many years ago, and basically got tired of lugging that much weight and bulk around. I ditched everything a number of years ago, and haven't regretted it a bit.
If half-frame is good with you, then please read the following -- Sony, Nikon, Canon, Pentax -- all are very good. However, there are a lot more Canon users out there, which also means that there is more used Canon equipment out there. On one of the forums I frequent, there are probably ten times more used Canon lenses for sale over Nikon. Something to consider if buying used. Personally, I would go with Canon or Nikon, as lenses are easier to come by. And between these two, you will sometimes find Canon-mount lenses on sale at popular retailers, while the same lenses in other mounts are not on sale.
That being said, I use a Nikon half-frame dslr, and am very happy with it. Half-frame is fine for my needs and desires, and I use my Nikon when shooting wildlife with a big Sigma telephoto. I don't use it for anything else. For the rest of my photography, I use an Olympus micro four-thirds camera and a Fuji p&s. As with my Nikon, the size of these two cameras suits my needs and desires just fine. If you haven't already done so, you might research the pros and cons of the different popular formats before you decide. After all, it is good to have alternatives..........