It's amazing that we've managed to man up so many aspects of your life before making our way to this, the access point to your man knowledge.  Your man-ledge.  Ehh... it doesn't work with every word.  At any rate, the most preferable option to man up your computer is to acquire an already manly computer, like one of the following. 

The WarGames Computer

Of course, if you're going to get the WarGames computer, there is one caveat:  you can not be Matthew Broderick.  Actually, in general, if you're Matthew Broderick, you're pretty much wasting your time trying to Man Up anything.  You'll just end up Matthew Brodericking it up, and that benefits no one.  Everything comes out sort of smug and nasal, and you'll be married to Sarah Jessica Parker.  It's a bad deal.  At any rate, using the WarGames computer, you will be able to enact the plan of global devastation you've dreamed of ever since you were manning up the A-Bomb mobile above your tank-shaped crib.  

ENIAC

The first computer suitable for general use, it's the sheer mass and earthiness of the ENIAC that makes it great.  It cost over a half-million dollars to build in 1946, which is in today's dollars -- according to my calculations, computed on my own ENIAC -- about seventeeny million dollars, which is not even a real number.  Also, it's important to note that I don't know how to operate its punch card data input system; I just put pictures of naked chicks in and hope the computer will repay me in kind, or at least rate them on a scale of 1 to 10.  Also manly about this computer?  It takes up almost 700 feet of floor space and uses 150 kilowatts of power.  To put that in perspective, you could easily power a farm with that.  Real men love gross inefficiency.

A Cyborg 

Any cyborg will do, but make sure that he comes equipped with either a laser rifle or Tesla coil fingertips, he can read your mind in the future and answer your queries before you've even thought of them, and he should be able to print pictures out of his mouth.  He will be your sidekick, as you will provide the quick wit and the swashbuckling style to your team, and together you will defeat the Space Chinese and end their nefarious plot to assassinate the King of the Moon.

A Missile

All missiles have onboard computers for targeting and stabilization.  If it makes you feel better about its lack of general functionality, at least you can call it your IBM.  It stands for I Blow-Up Motherfuckers.  Take that, other acronym.

The Last Resort

If you absolutely can't acquire any of these monsters of infeasible yet manly computing tenacity, there are two separate mods you can apply to your current machine to man it up.  One is specifically designed for desktops, and one for laptops, so we should be able to cover everyone... and both involve beer.

Dealing with the desktop first, let's take a look at what you can accomplish with a little ingenuity and a lot of putting-a-keg-inside-your-computer-case.  Particularly brilliant about this design is the fact that the refrigerant which keeps the beer cold also allows you to overclock your CPU to unheard of speeds, which in some unfortunate cases has actually caused the entire computer, keg and all, to travel back in time, so -- although it's never manly to be careful -- remember that there's beer at stake, and don't get greedy.

Finally, this is how you man up your laptop.

"Ohhh, but either of those options could cause beer to spill on my precious computer," you say.  Well, guess what?  If you spill beer on your precious computer, you're fucking doing it wrong!  Anyway, maybe you should have thought of that before you let superbilly133 outbid you for the cyborg.

Ah, the wonders of computing, at last delivered out of the realm of horrid nerd-dom and into the hands of those with the knowledge and skills required to MAN UP YOUR COMPUTER!