I have pretty much the same T60 laptop with the exception that it has 3GB of RAM.
It has a 32-bit CPU so you will be "limited" to using Ubuntu-based distros that are built on 18.04. It is still a useful laptop with a few caveats:
- It will be supported til 2021 for Ubuntu MATE
- It will not will be "fast"
That said Ubuntu MATE works very well on it and it is able to handle almost anything you'd like to do. That being said mine is used almost exclusively for testing now.
I would recommend burning the ISO's you've downloaded onto a USB and run the laptop off of the Live USB and see how the performance is to you and choose the one that suits you best.
Good luck and have fun.