Yes XP will support SSD, the only thing you will not get support for SSD is the TRIM.
If I am not wrong, the only OS you get TRIM support is Windows 7.
I think if you have 2 Gb of ram, you will be fine to stick with Windows 7.
I think all your hardware you will not have any problem upgrading to a newer Windows, I think you should try and test yourself.
IMO, it is better than XP.