The capable ($80; free demo) has been my go-to recovery application for years because it works with every file system out there, including Linux and Mac. The interface and approach are a bit technical, but R-Studio does the job if the job can be done. The demo comes with its own boot CD in case you need to recover from a machine that can't boot to its OS; I always try to attach the ailing drive to another computer since Windows-based recovery is faster, but it's a nice feature. The demo recovers files of 64KB or smaller.
Active File Recovery is another of my favorites. Although I wouldn't describe the interface as dead-simple, ($35; free demo) makes it a tad easier to see what's recovered than R-Studio. Also, it's relatively inexpensive, and the demo recovers files up to 64KB. Companion product ($40; free demo) has also delivered good results. In many cases, by restoring a partition you'll be able to boot to the OS again--and if not, you'll at least be able to use standard file-copy methods to recover your data. For the latter, you'll probably have to boot from a CD; any version of Linux that will run from a CD, such as Slax or Ubuntu, is suitable and free.
For only a little more money than the Standard version, ($45; free demo) combines both file recovery and partition recovery. Hint: Buy Professional unless you need a boot CD, in which case the Enterprise version ($100; free demo), which comes with a Windows 7-based boot CD, is appropriate. Again, the demo can recover files up to 64KB.
Other recovery utilities are out there, including the very pricey ($200; free 30-day trial) from Ontrack, which I've used effectively as well; its demo can recover a single file. But the programs I've discussed above have worked for me consistently over the years. It doesn't pay to mess around or to try to cheap it out when your drive might be dying even as you recover data--so don't risk it.
That said, in my tests the sector-based recovery in the latest iteration of Recuva worked fine with IDE drives (though not SCSI). If you're sure that hard-drive failure isn't imminent--it can be when you start seeing errors--give Recuva a shot.