A PIC would be more fun.  Depending on your requirements, you might be able
to use the sound card or the multimedia timer on a PC.  There are a lot of
sound card oscilloscope applications out there. Sounds cards are AC coupled
so they can not be used for DC signals or low frequency signals.  It sounds
like your application may not be suitable.

http://www.inesinc.com/sound.htm

http://polly.phys.msu.su/~zeld/oscill.html

> I am doing some consultancy for a company at the moment. They have a
> need to measure displacement of a vehicle suspension, at bang on
> 50Hz. They have so far set up an elaborate system which moves a PC
> mouse, and tried to create windows software to read the mouse
> position 50 times per second. However, they've been having great
> difficulty in reading at that frequency, and in particular, reading
> without a fair degree of variance over the frequency.
>
> I have been hired to help them out. The main problem they're having
> is the way windows works. It's not a Real Time Operating system, and
> the internal clock pulse of the NT kernal has a period of 7.5ms,
> which makes it really hard to do anything in real time at a frequency
> whose period is not a multiple of that.

You can reconfigure this down to a 1 ms resolution.  In the past I have used
the multimedia-timer on NT 4 to run real-time hardware-in-the-loop
simulations at a 3ms rate.  It worked fairly well but it will still not be
hard-real time.

If you want to use a PC, and have real-time sampling, National Instruments
has plenty of solutions that will stream real-time A/D samples to your
hard-drive.   The hardware does the real-time sampling so it does not matter
that Windows is not real-time.  National Instruments supports a widde
variety of data aquisition cards; PCMCIA, PCI, USB, FireWire, etc.

http://www.ni.com/

-Ed

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