When I upgraded my Windows laptop (running Windows NT) from something like 64 MB to 128 MB, it made a huge difference. Most of the benefit was that it stopped using swap. Sadly, I was borrowing the the DIMM from my boss and I had to give it back. It was like flying back on coach after getting there in first class.
I still have it, and when I put an 32bit version of Debian on it a couple years ago, it was molasses. Somehow I used it for years with no complaints.