1. SSDs are really only necessary if you need low boot times or if you work a lot with file copying. If you're not a programmer, you don't really need it. But as G_G said, it's nice to have.
2. What G_G said about page file and hybernation file is true, but you can disable both of them and free up that space. If you have 16 GB of RAM, you will hardly need more than maybe a 2 GB pagefile just for being on the safe side. You can get rid of the hybernation file completely, it's not worth it.
3. 128 GB SSDs are cheap nowadays, I recommend you get that one instead of a 64 GB. Maybe you can get even larger drives for a reasonable price.
4. Stay away from Seagate and Maxtor, their drives are worth crap. I've had problems yesterday with my laptop and when I did a surface check on my system partition (which is 50 GB on my 500 GB HDD), it had 9 read errors! After only 2.5 years of usage! I shudder to find out what the other 450 GB looks like.
A co-worker of mine also said that Seagate (and Maxtor which was bought by Seagate) HDDs are crap. Best you get a Western Digital, those have never failed me so far at least.
5. Really not sure about the GFX card since I had both good and bad experiences with both ATI and nVidia, but those were low-end or mid-end cards as I never used high-end cards. Have you thought about using 2 weaker cards for SLI/Crossfire? You might get better performance that way.