Several things to be aware of when capturing video to a PC.
1. you need a fairly large amount of disk space 2Gb for 10 mins (roughly) Using a standard DV compressor.
2. Don't capture in Uncompressed.... file sizes are unspeakable.
3. Defragment your hard drive. (Drives fragment over time as files get moved deleted and so forth.) Free tools can be found all over the net on trials and freeware. A heavily fragmented drive will severly reduce the capture performance and you may find your PC dumping \ dropping frames.
4. Use an adequate processor, not really a direct impact upon the capture, but can have an effect on the program running it (especially if there are multiple background processes running)
5. You may want to disable your virus scanner if you have one (and disconnect from the net) The virus scanners can be set to scan incomming files, entire drives folders and files etc.... you don't want this program requesting read access to areas of your drive while you are trying to write to others.
Disconnecting from the net is just a general good idea (my flatmates drove me insane by sending net messages to me while I was copying)
6. Memory not that important in the actual CAPTURE (unless it's being captured to anything like MPEG) but as it's cheap as chips, you may want to top up :)
7. Expandin on the above.... capture in AVI. It's cleaner and easier to work with (and you need type 1 or type 2 AVI files to export back to most camcorders.
8. Limit the number of programs running (you said you did this already, but I am wondering if you are terminating the processes by using the icons on the bottom right (near the clock) or by using Ctrl + Alt + Delete and selecting the processes there.... (Don't do this unless you know what you are doing)
9. Win a lot of money and get the most stupidly fast machine with lots of memory and disk space....... I'm still working on the winning bit.... I am a wizard.....