im ordering parts tonight and im still deciding wheather i should get a new motherboared and ram or get an ssd that will be running in sata II till i get a new moterboaed and ram which might be awhile,
I would go for a sata 6 based SSD, even with a slower system, its a night and day difference. Just make sure to format it as 4k and AHCI.
Motherboard and ram I would be getting at the same time as the new cpu, generally in regards to cpu, motherboards etc every couple months ~6 they release new stuff, so, to get just ram is one thing, but to get ram motherboard without the cpu, to me is silly(course this depends on the cpu you have)
I would go SSD 60gb minimum 90/120gb prefered as then you can have a game or 2 on it without worry, 60gb as JUST an OS and mandatory stuff can be done, but it doesnt leave much room to play with.