HD Master File Codec for Windows

First of all,
hi to everyone :)

I am still green on the video editing thing so bare with me please ;)

I just finished a project in Premiere CS 5.5. I mostly use HD footage from my DSLR with some AE clips thrown in.

Now I want to create a Master file for archiving and future export purposes. From what I have been reading, the best option is (probably) to use a lossless codec. So, the options tested so far are:

1) Lagarith in AVI container

Pros:

a)Works well, smaller file size

Cons:

a)I have read comments claiming that it does have problems preserving original information on the luma key. Now, I do not have a clue what they were talking about, but it seems to me that they mean the Master file is actually worse in some way, compared to the original (which is just plain weird since this is a lossless codec....)
b) Not compatible with OS machines. Not that I need to share now, but you never know what the future holds.


2) PNG in Quicktime container (mov)

Pros:

a) Is universal
b) Quality is 100% identical to original

Cons:

a) File size is huge
b) Takes ages to render, in windows at least...


I need a solution that will be:

1) Future proof (and hopefully universal)
2) Good for exporting and re-editing if needed in Premiere Pro or other app in the future (again Windows is the platform if choice)
3) Will be truly lossless (no quality hits, no programming bugs, etc)

Thanks, and sorry for the long read :)