My situation

I know that bitlocker is meant to encrypt whole drives, but I have an hard drive that is already fully partitioned and containing data.
I'd like to encrypt part of one partition, leaving the rest of the partition accessible.

I would very much like to avoid programs like Norton partition magic (which resize/split partitions), because every time I used them I had problems with the data stored.

Question

Is there any way/builtin alternative/3rd party app that integrates with windows login to encrypt one subset of a partition?

EDIT

I heard horror stories about EFS, which is why I don't want to use it.
Some highlights from that article:

In fact I’ve only used EFS twice in the last ten years on my own computers and on both occasions I’ve lost files and documents. I therefore cannot recommend you ever encrypt your files with this Windows feature.

Unfortunately, because of incompatibilities with some differing versions of EFS files can end up scrambled and unrecoverable.