Best upgrade choice

How much you looking to spend? I state the obvious that most things are pointless to that setup but as you plan to move platform as you say it can carry over.

SSD is one idea would carry over but how about a new kick ass GPU? would be amusing as hell introducing your athlon 64 X2 with gtx670   or another 460 (while they can still be got) to sli in your new setup later on?

can't do sli with this board, and i'm looking a $150 in gift cards.

I doubt there is any upgrade you could do that would have a visible effect today that would not ultimately be a waste of money.
Right now, the weakest part of your system is the CPU. The trouble there is, any money spent on an AM3 CPU (will work on your AM2+ board) will still be a waste. When you build your new system, it will almost certainly be Intel. Any possibly competitive CPU that AMD might release between now and then will not work on your older board.
You could buy a stronger graphics card like a HD7850, but it will be badly bottlenecked by your CPU; you might see a little gain in some games, but won't get the real benefit from it until you move it to your new system.
What PSU do you have (brand and model, not just wattage) ?
How much money are you looking to spend right now?
What applications and/or games are you wanting to run?
What is the resolution of your monitor?

Edit: Ok, saw the budget. Your best carry-over items are either a quality PSU or a 120GB-128GB SSD. You can get the other of those two later when you rebuild. If you've got a cheap one now, make the PSU your priority.

SSD then or maybe a fancy case

already have a AZZA case full tower 3 80mm, 1 120mm on side. psu is likely weak for my future needs (500), so it seems that mb wise an ssd is the only part
to upgrade right now and see a performance difference that will move with me to the upgrade but still get an impact right now?sorry ya'll I kinda piece em together.

What brand and model is the "500W" PSU?

sorry about the late reply the power supply is bfgr450wgspsu

playing diablo 3
skyrim
mass effect 3
monitor is an acer h233h (1920x1080)HD

The BFG LS450 got an excellent review at jonnyguru. Is that the one you have? You will want a more powerful one for a new rig, but it should be fine for now.

seems to be an r450

seriously considering this for now http://www.newegg.com/Product/Product.aspx?Item=N82E168... leaves some money for something else not sure what though.

That would be a nice choice. Why not save the rest of the money for when you build the whole new rig? Budget flexibility then is likely to be worth more than a minor upgrade now.