As far as the slowness. The ram and SSD upgrades will help. But it is still a 7 year-old computer. With older architecture, slower cpu, and older/slower graphics.
I happen to have a 2008 MacBook (slightly newer than your's)...with 4gig of ram...and a "shrimpy" 40gig HD I popped in it. It is very similar to your MacBook (slightly faster cpu, same graphics hardware)...running OS 10.7.5 (Lion). And it does pretty good for it's age.
So your 2007 MacBook with the upgrades should be pretty useable for many tasks. But if things get to be too graphics intensive...this is where it will show its age.
This is why if you were able to sell the computer + the upgrade money...you could buy something used a couple years newer...and be much more capable (for basically the same money you currently have invested).
But like I said...the 2007 will be fine for many tasks (at the moment). And it can be a hassle to sell a computer...and then try to find an newer used one. So it's up to you...and how much effort you want to put into a project like this..
HTH,
- Nick