If you mean mini pci-express card, that is an internal card and most likely won’t work for your purpose. A PC card (formally pcmcia card) will work in most laptops/notebooks, and PCs specially equipped with that interface, but usb will work in all the above, being every variety of computer uses usb these days. The disadvantage is usb devices can be awkward and often stick out of the laptop quite a bit and bumping them can sometimes damage them, or the laptop. For occasional use, I’d say usb, for regular use, PCcard, but the choice is yours.
i am going to buy a sim card reader for my laptop , so that every where i can connect to the internet …
It won’t do that. A card reader is just that, something that can read a card. It doesn’t connect to the internet.
You don’t need to read a card. You need to use it, in (e.g.) a cellular modem, in order to connect wirelessly to the internet. It’s the modem that you need, not a card reader.
You will not be able to bittorrent at speed though, because you will not be able to have an open listen port. All cellular modems of whatever sort, are firewalled.
You will not be able to bittorrent at speed though, because you will not be able to have an open listen port. All cellular modems of whatever sort, are firewalled.
can i do common web exploring tasks (like email management and forum loging , posting in blogs … ) ?
You can do any Internet related task with no problem whatsoever just like with any other Internet connections (xDSL, cable or optic fiber). Some of the mobile internet plans offer quite decent navigation speeds too (around 8Mb/s download or even higher).
It’s only the applications which will need an open listening port that will have problems in working as they should.
Most applications don’t need that (browsing the web, retrieving email, IM, chat, Skype and most other common Internet-related apps don’t need an open listening port), however BitTorrent clients and a few other apps DO.
Just make sure that as kluelos pointed out, if you decide for an internal card (ExpressCard or PCMCIA), you check that it includes a MODEM not just the SIM reader, since it’s the modem device that will connect you to the Internet (the bare SIM reader part will at best transform your laptop into a mobile phone).