I own FRAPs and Playclaw, but my current favourite is DxTory (
www.dxtory.com ), Bandicam is quite good too. There is another one called 'Action', but I haven't used it for ages, so can't comment on it now.
The good thing about DxTory is striping (much like a RAID array). You
can record direct to an .avi anyway (one single file), like the other programs, but if you want, you can use striping, where you can save to multiple drives at the same drive (RAW format), and use as many drives as you want. This eliminates any one drive 'choking' because too much data is being transferred and it can't cope (or the controller can't cope) for some reason. For high bit rates it reduces the chances of frame drops and stuttering.
Like a RAID, the captured video data is sent as a chunk (or perhaps a frame), to one drive, then the next bit to the second drive, and the third bit to a third drive, and so on, depending on how many drives are setup. Naturally in the 3 drive setup above, after the 3rd drive it goes back to the first drive.
The software has an in-build facility to preview the video in it's currrent RAW format, and then to compile the video as one .avi file to another drive perhaps (your choice).
Currently I stripe to 2 drives, and compile (reassemble) the final video to a 3rd drive.
PS. There is no use in striping to 2 partitions on the same drive.