I think xheavy misunderstood your first post, and thinks you are going to raid several SSDs through a raid card, when all you want is a SATA controller that your SSD would plug into.
While the SSD would not be entirely wasted on your machine, there is a point where your core system should take the priority, and this may be one of those times, and adding the cost of a decent controller card to the cost of an appropriately sized SSD, you would be most of the way to a new mobo, proc, and ram.
Thankfully you do not need a SATA3 control card to run an SSD, a SATA2 will do just fine (you may have issues with a SATA1 card), but be aware that those control cards tend to have a 10-30sec timeout (depends on the card) when booting up, and Windows can get picky about booting off of one, so you may have better luck with a new platform in the end anyways.
64GB isnt a whole lot of space. I put a 60GB in my wife's computer and with just her basic slavo of office, sibalious, chrome, win7, and a few other small programs it is up to 50GB. Thankfully I have it set up so everything saved to 'my documents' automatically goes to a 500GB HDD, so hopefully there wont be a long term space issue. For my own use I was up to 180GB in software (on an HDD, no SSD for me yet) before I reformatted last week for my new build, and that is all software and keeping all save files on other drives.
I would suggest going for a new Pentium Gxxx processor (with HD2000 graphics), or a new AMD APU. Then load up on 4 (1stick)-8GB(2sticks) of ram. The intel will have a better processor, while the AMD will have better integrated graphics, but either would be a good upgrade for you.
AMD APU/mobo itx and 4GB ram (fanless!): $112 (including shipping)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
AMD APU, and mobo: $136
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Intel CPU and mobo: $135
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
for either of the last 2 builds I would go with:
$20 4GB (single dimm)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
or
$40 8GB (2 dimms)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
With any of these 3 builds you will need a cheap PATA to SATA adapter $5 to reuse your current HDD. Then, instead of turning the computer off at night, put it to sleep (not hibernate), and it will turn back on very quickly relieving you of the slow boot times until you can afford to add a more modern HDD, or SSD (the fastest mainstream PATA HDDs only hit a sustained 60-70MB/s, while newer ones like mine will sustain 120mb/s). Modern sleep mode takes nearly no power, we are talking just a few dollars a year to leave it asleep for a whole year, which will be made up for in much lower active power usage as these are much more efficient than the current setup.
Again, you are right, the SSD with a controller card will do the trick, but these options will bring things up to a level where you can better take advantage of an SSD in the future without having to macguiver it into working.