[Solved] The Upgrade dilema

So I am running an AMD 4600 Dual core Cpu. I have 2 gigs of OCZ DDR2 Ram in a relativly cheap MSI motherboard. I am also using a 4850 ATI video card and a Fatality creative sound card. Overall I try and stay about 2 generations back from the leading edge of hardware for cost reasons. Well naturally it's about time for me to kick up a few levels. Thankfully I recently replaced my badly ageing 1600 ATI video card so I am pretty happy with the 4850. I am looking at ram, I switched to vista 64 bit for DirectX 10...somewhat happy with that decision. I plan on switching to 4 gigs of ram. Well naturally the issue is, DDR2 or 3. This board only takes 2 so I would need a new board. I would like to switch to a new AMD CPU as well, a quad core, thinking the new Phenom BE. However some of these I can get running DDR3. Well I would need a new board.

Question comes down to, does it make sense to run cheap and just get some DDR2 ram and have 4 if not 8 gigs of ram for easily under a 100 bucks and get a newer CPU and be done. Or just spend the money and get a decent 100 dollar - 200 Dollar motherboard and new DDR3 ram and CPU? I can save the money for that switch and wait it out, just wondering if it would end up being really worth it persay. Would I really notice the speed difference in the end?

Oh, ram follow up. Was poking around newegg last night. I have OZC ram right now, 2 1 gig sticks. Initially I had one stick die within a month of purchase and just swapped them at the store, been fine since. Was looking at muskin ram last night but I know corsair and kingston make good ram as well. Heard good things from G.skill. Same issue though, do I need to go past 800 in speed department, this board I think will only take 1333 as it is but if I am buying it might as well buy some good ones.

I would go with Outlander_04's suggestions above.