only if your working as a straight actuary
combined is good, but it depends on what you combine with.
comp sci is good, cause you'll need alot of computing knowledge when you go out to work, and its good to have that familiarity with the progs (so I've been told)
with sci, depends on what you want to do with it. most people go with maths, again to supplement their actuarial understanding.
I believe though, that straight commerce degree is mainly what companies like to look for - mainly finance. people I know in the workforce have said that its a very good combination, because it induces alot of respect, and so its easier to jump into management and higher paid jobs. the actual finance side itself doesn't do that, but it provides the background that companies like you to have about the economy, etc.
you'll find that the co-op people are made to do straight commerce (though I *think* some still do actuarial studies and maths).
all that aside, if your looking for advantage, then that's what you go for.
if you can make actuary alone however, you're still at a great advantage, because of the demand that's being generated for it.
so choose what you like. even if you don't like the above, just choose something you'd enjoy as well (I'm doing physics for example)