[MacReader]

Hi there. This is my first post so a bit of background:

I have not actually purchased a reader as of yet, but am looking to buy a Sony PRS-505.
I am not looking for a lot from my reader other than being able to read books. I do not have a problem going to my computer to transfer my books since I am there most of my waking moments anyway. So, the advantages of the Kindle for me really don't give me much incentive to spend the extra cash on those features (wireless, etc).

My main concern is that I am on a Mac which has lead me to my investigating Calibre. Most of the features look great to me, but my main concern is getting the Mac support for the Sony 505.

My main question here revolves around the purchasing of ebooks.
If I buy a book from the Sony ebook store (which has no Mac support) will I be able to get the book from my Mac to the reader? I know that the books they sell have DRM and that Calibre doesn't remove the DRM, but can it simply perform the transfer?

Also, what other alternatives might be better places for purchasing the books. I've done a bit of searching here but no one really seems to have a large inventory. The inventory issue would be the only thing that makes the Kindle attractive to me, but maybe there are alternatives. I would prefer to have a one-stop-shop for purchasing books but if it's easy to purchase from multiple places I'm not terribly averse to it. Especially when I view how Calibre can help me in the organizing of them once purchased.

At any rate, I appreciate any advice all of you can give.

Thanks