is it better than the mouse? I'm doing painting with Corel Painter or poser .. everytime i had done projects with poser , at night i will wake up with numb hands. so i think the mouse is really bad for us. i have a wacom tablet with a stylus but i have't yet used it that much

Changing styles and positions is much better for your hands. Uses different motions and parts of your hand, so, any less use for a certain part reduces wear on that part.
Aside from that, tablet gives you a LOT more control when painting things. I wouldn't do what to do without one.
Personally I use a combination of a lot of keystrokes (not a big fan of menus if I can keystroke something in three keys or less), I got myself one of the programmable gaming pads for keystrokes in higher end apps. I'm constantly switching between a keyboard, mouse, tablet and a game pad. Having 20+ years of mousing wear and tear on my hands I kind of worry about those things.
And do a lot of hand (and body) stretching and exercisng.

I get hand cramps from holding the stylus to long as with the mouse. I switch every so often when I can so it's not the same thing all the time. I also use a mouse pad that has a wrist pad to support my wrist. That helps a lot.

Certain things are tremendously harder for me in 3d apps when trying to use the pen, mostly camera control (nearly impossible to rotate a camera very well with a pen).  For some things, particularly painting and drawing of course, it's great to have needle point control - but sometimes you really just need a brick.

numbness in the extremities can be caused by several factors. the devices used by the hand may be less a factor than certain underlying medical conditions. as mentioned before, if the condition persists, you should see a doctor about it.

When at your computer (home AND work) do you rest your forearms, elbows or wrists on anything??  If so...  STOP!!!!  I have Ulnar Nerve Dysfunction in my left arm as a result of propping my elbows up on the desktop of my cubicle for an extended period of time.  Since then I have no feeling in the last two fingers and half of my left hand, pain emanating outwards and up to normally my elbow but at times all the way up to my neck!!!  If you have to rest your arms on your desk to work at your computer then you need a higher chair or a keboard tray under your desk to enable a better position for your arms and shoulders which will lessen strain on your extremeties!

Hope that helps in some way!

Gerard

Ghelmer, I'm sorry to hear that :(   It makes so much sense, when I think back to what I experience.

I always had a hard time with neck, back and arm aches with certain desks (later found out they were improper height) and always HATED the chairs with arm rests. Sure, short term they were comfy, but I would notice they would always get me in theese positions that would make my body hurt, and they would sort of promote bad posture. I always insted having a less comfy chair, but one promoting good posture.

Luckily, with a good dose of arthritis, my elbows hurt a lot after ten minutes or so of resting on a hard surface, like a desk!

@pjz99 - love your brick analogy, it's sooo true!

on second thought, the combination of numbness in the extremities and blurred vision is of greater concern than either alone IMVHO. I would suggest tebop see the doc ASAP.

Yeah, both can be signs of neurological things going on. 
Could be as simple as, and considering lot of computer work is very likely to be, a nerve in the neck pinched by a overstrained cramped or prolapsed muscle, needing a chiropractor, relaxing, better posture and a good massage. .... BTDT

In my case I think my body is paying me back for all the 'I can work at the computer for 20 hours straight if I need to' I did in my 20's.

I use my right hand to mouse at work and left at home and that helps a lot.

A good chair and lots of room for your arms on the desk will help more than a tablet.  But, you really should see a doctor - if the pain is waking you at night you are getting to the nerve damage level.