Well you can get a gtx460 for $119 after rebates, or for $139 without them on newegg.http://www.newegg.com/Product/Product.aspx?Item=N82E16814125412http://www.newegg.com/Product/Product.aspx?Item=N82E16814127646
Another option is the gtx550ti for $119http://www.newegg.com/Product/Product.aspx?Item=N82E16814125410
The gtx 550ti is newer than the gtx 460 but with your tight budget they are still better than the gts450. If you can, go get the gtx460 as it performs better than the gtx550ti, and it costs more or less $10 more. These cards will allow you to do anything you need, and you can game pretty well on them, maybe not at the highest settings and resolutions but still much better than the gts450.
Hope this helps!