I'd probably do this using either Image Processor, as Jeff suggested, or right in the Camera RAW window. (btw, Image Processor is in Bridge, under Tools>Photoshop, if memory serves. There you can set all the things like what images to use, where to process them to, etc)
I will often just open the stuff I want to work on in Camera RAW, and setting adjustments there, as well as sizing through the Crop Tool (hold it down and select "custom..."), then Select All and Save (button is at the bottom left corner). Then you're in a window similar to the Batch, or Image Processor window (maybe they're all related under the hood, not sure), and you save as whatever you want. With Camera RAW 5.2 you can also apply sharpening now int he Workflow panel, I'm not sure if that applies sharpening to processed JPGs too... Jeff?
With a quantity like 300, I'd do it in parts of whatever your system can handle, but I like to go through every image, even just for web gallery/approvals... so this works pretty well.