Canon has this information on their website but it is presented in a manor that makes it difficult to understand.

My best guess is as follows:

512 meg card:

(Video format is .avi)

630 x 480 at 30 fps - 249 seconds (4.15 minutes)
630 x 480 at 15 fps - 487 seconds (8.12 minutes)
320 x 240 at 30 fps - 702 seconds (11.7 minutes)
320 x 240 at 15 fps - 1,373 seconds (22.88 minutes)

.....

You can also use an email compact mode, with a limit of 60 seconds per clip:

160 x 120 at 15 fps - total 3,357 seconds, but in 60 second clips (55.95 minutes)

.....

There is also a Full Motion option, with a limit of 180 seconds per clip:

320 x 240 at 60 fps - total 359 seconds, but in 180 second clips (5.98 minutes)

...
..
.