As Rusty said, 200 ppi (pixels per inch) is about the minimum you want for a decent print. Higher for more quality prints. So for an 8x10 you would want it to 1600x2000 minimum. I try for at least 300 ppi when I am considering printing a photo. Or even higher if I can get it. Your camera will determine how much you can crop. You will not be able to crop as much if you are shooting a 6 Mp camera as you could shooting a 16 Mp or higher. While PSE and PS can do a fair job of enlarging, there are programs out there designed specifically for enlarging photos.
OnOne's Perfect Resize 7 is one of those. The full standard version costs $159.95, while the full professional is $299.95. But if you are starting from a crop that is 69 ppi, you are already behind the proverbial 8-ball. One suggestion when cropping, leave the ppi box blank. I find this gives much higher ppi values afterwards. The absolute best though, is to get your composition as close to correct as possible in camera so you can keep cropping to a minimum.