Worth one more upgrade?

ORIGINAL SYSTEM - built 2006

• Intel Core2Duo E6300 1.86Ghz
• Intel DWG965
• 2Gb DDR2 800Mhz
• BFG 8800GT (2 in SLI)
• Creative X-FI Extreme Audio

Last Upgrade 2010

• Intel Core2Quad Q9450 2.66Ghz
• MSI P7N-SLI (used gift, about 4yrs old?)
• 4Gb DDR2 800Mhz
• EVGA GTX465
• Creative X-FI Extreme Audio

I have been out of work, and upgrades were possible due to friends upgrading and giving me parts that were better than what I had in my system.
I have recently started a job, but need to save for a car and laptop for work.
2 years ago I upgraded the PSU to a 750w

I have to budget under $200 and prefer to spend as little as possible so I am considering:
A Gigabyte board at Newegg(GA-G41MT-USB3) so I can also upgrade to 8Gb of DDR3

What concerns me is:

• will a new board vs a 4 or 5 yr old board make a difference?
• will it help to be on DDR3 and better RAM speeds to match CPU FSB?
• will it hurt going from PCI-e 2.0 down to 1.0?

I need to try get another year or so out of this system, and I don't even know the diff in DDR3 ram speeds really.

PS: MAIN USE:
CoD Black Ops, BF BC2, Gaming Community & Game server management, some photo/movie editing and DVD burning.

I dont think faster RAM and a newer motherboard are going to give you a noticeable increase in gaming performance to be honest. I would just stick with that until you have enough cash to get a new mobo, CPU, RAM or entirely new system.

have I not provided enough info?
does no one have care or opinion on new mobo vs 5yr old mobo?

I was told it would make a difference, but did not trust source, so I thought I would post here and see what people had to say.