would this be a good build? for the money
Yes; things are compatible. I like the 2500K which will be good for a long time.
For ideas on saving:
1) A case is the easiest place to cut. I like the Antec 100, buy it if you love it.
But, you can get a nice small case like the Rosewill FBM-01 . It was used in tom's recent $650 build:http://www.tomshardware.com/reviews/build-gaming-pc-overclock,3159-5.html
2) It is a M-ATX case, so you need a m-atx(smaller) motherboard.
This asrock will save you a bit there too:http://www.newegg.ca/Product/Product.aspx?Item=N82E16813157270
3) Ram speeds do not make much difference with sandy bridge. 1.5v ram does not need heat spreaders either.http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3
This g.skil kit will save you a few bucks:http://www.newegg.ca/Product/Product.aspx?Item=N82E16820231422
4) A 550w psu will run any single gpu up to a GTX570, or even a GTX680 or 7970. If you ever want more than a GTX680, you are in an entirely different class of gaming.
I see little value in planning for more via sli.
Here is a corsair CX600 for a bit less:http://www.newegg.ca/Product/Product.aspx?Item=N82E16817139028
5) Hard drive prices are very high today. In time, they will come down.
Consider deferring the hard drive and build using a SSD for the os and some apps. A 60-80gb drive will hold the os and a handful of games. Prices should be around $1.25 per gb or so. I like Intel 520 series for the 5 year warranty, but Samsung 830 is good too. Look for rebates on Intel 320, There have been some big ones recently.
5) For a first build, I suggest you download and read, cover to cover the motherboard and case manuals.