For what it's worth, I upgraded a 5150 to 2gb RAM, 120gb SSD and clean-installed Windows 7 Professional 64-bit yesterday.
Everything works, and it pops out of S3 sleep in seconds. The owner is pleased, because it's much faster than the old spindle drive-installed OEM XP and the soon-to-be- end-of-life XP is now supplanted by a modern version of Windows.
There's life in these old machines yet!