I know there is already a topic about it but its locked that's why I am posting a new one, I just want to share with those who wanted to install and use whatsapp on PC and if you already have it good for you :)
As the previous topic mentioned you will have to get youwave from :
http://youwave.com/
Its an Android emulator, its a 14 days trial version I guess but if you search around you can get a "patch" for it for unlimited use. (PS: this has been tested on the latest youwave 2-1-2, I tried it on 2-0-0 it didnt work).
After getting youwave install it and you will have Android running on your PC in no time, go to
www.whatsapp.com download and install whatsapp like any other software (inside you wave of course).
Now here is the tricky part, the registration, you will be prompted to enter a phone number to send an sms to it, dont enter your cellphone number or else it will stop working on your cellphone, I did it first and I had to reinstall whatsapp on my phone again, what you have to to is enter a local Lebanese landline number ;) yes something like (01XXXXXX or 04, 05, 07 ....) but this landline must be a valid number that you can receive a call from it. Now whatsapp will try to send you an sms for verification and will launch a 5 minutes timer, after the 5 minutes are gone it will tell you sms verification failed and give you another option to register, you will be offered an option "Call" press on it, then within seconds the landline you submitted will ring, pick up the phone you will here an automated lady voice telling you the 3 Digit code, you submit this code and whatsapp will verify it successfully :D
You can now use whatsapp on your PC, I have been doing it for 3 days now with now problem.
As for the contacts thing, its easy, you can go to "Contacts" on your youwave and add people manually, or simply sync it using gmail and when you want to give give your whatsapp "number" to new people give them the 01XXXXXX number as I did with some that laughed at me first and became speechless when they saw I wasnt kidding :P