so i usuallu aim for 45-60 min of cardio (3-4 times a week), im trying to lose weight and tone up...is it better if i do the elliptical for the whole duration or is it also good to mix it up? 20 min treamille 20 strider and 20 efx elliptical?!
would i get the same benifits?

It doesn't really matter either way. As long as you keep the gaps while changing machines to a minimum (don't let your heart rate drop if you can help it) you can swap equipment as much as you like. Variety can be very useful, just don't let it be your focus compared to heart rate, intensity, and duration. :)

I don't agree with not letting the heart rate go down in between machines.
Studies say that doing 10 minutes cardio 3 times per day is actually just as effective as doing 30 minutes straight.
HIIT (high intensity interval training)is also very effective for weight loss and doesn't require endless workouts on machines.
My two cents.

This is true! Many people get great results from interval training. I think either way would work fine for you though. I'd actually suggest doing different things so you don't hit a plateau. Some days, only do the elliptical and others you can try other things. It keeps you from getting bored as well. You can also alter the speed/resistance/incline that you use to keep you from hitting a plateau.

Remember, that you will get the best results if you add in some strength training too. You don't have to do any heavy weights of course... even some light dumbbells are good to have. I do about half an hour of cardio 5 times a week and do different exercises using weights. I have been getting way better results than when I used to do only cardio in the past. My arms are nice and tight, but not muscular. My legs are now my favorite body part and are very firm from all my running as well as lunges and squats. Then of course it's good to do some core exercises as well! I usually do basic crunches mixed with side crunches and bicycles. You can definitely do many different exercises rather than crunches if you don't enjoy them.

I don't agree with not letting the heart rate go down in between machines.
Studies say that doing 10 minutes cardio 3 times per day is actually just as effective as doing 30 minutes straight.
HIIT (high intensity interval training)is also very effective for weight loss and doesn't require endless workouts on machines.
My two cents.

I would be interested in knowing your source for these studies. I mean no insult to you at all, but I have done tons of research on cardio, and never heard anything along these lines. It just really does not make sense. When your heart rate is elevated you burn more calories. If you work out for thirty minutes with a heart rate of say 160, that will burn more calories then three ten minute cardio sessions that have to climb back uo to that target HR, that is if they ever get there.

As far as the comment about HIIT, I agree that is a great method of cardio, and in my opinion the most productive.

is it better if i do the elliptical for the whole duration or is it also good to mix it up? Typically, "mixing" is better.

In general you should try to expand your exercise ability with regard to your current status. This mean that you should "try real hard" some of the time and "try to go longer or farther" some of the time.

When you do this, you develop two types of fitness, capacity and endurance. No single kind of exercise is ever the best routine.