Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Canon A1200 and Olympus E-510 side-by-side from the front, back and top in their relative dimensions. Canon A1200 has external dimensions of 98 x 63 x 31 mm (3.86 x 2.48 x 1.22″) and weighs 185 g (0.41 lb / 6.53 oz) (including batteries). Olympus E-510 has external dimensions of 136 x 92 x 68 mm (5.35 x 3.62 x 2.68″) and weighs 490 g (1.08 lb / 17.28 oz) (including batteries).
Below you can see the front-view size comparison of the Canon A1200 and the Olympus E-510. Canon A1200 is clearly the smaller of the two cameras. Its body is 38mm narrower, 29mm shorter and 37mm thinner than Olympus E-510. As you can tell, actually this is not a fair size comparison since Canon A1200 has a built-in lens but Olympus E-510 doesn't. Once you put a lens on E-510, its thickness will increase significantly.
Here is the back view size comparison of the Canon A1200 and Olympus E-510.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Canon A1200 is significantly lighter (305g ) than the Olympus E-510 which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on E-510, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Canon PowerShot A1200 nor Olympus E-510 / EVOLT E-510 provides any type of weather sealing in their bodies, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Compact Cameras with Weather Sealing Top DSLR Cameras with Weather Sealing
LCD Screen Size and Features
Canon A1200's 2.70" LCD screen is slightly larger than Olympus E-510's 2.5" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.