advice needed on windows or linux for hosting

Hello

I have set up my first phpShop 0.8.1 and am trying to decide which hosting package to go for.  My ISP offers both windows and linux (Both options have MySQL, PHP and Apache).  I want to use the phpshop checkout function so need to configure SSL etc.  One difference in the packages is that a private SSL is only provided with the most expensive linux packages.

So I have 2 questions:

which is better to use with PHPshop - Windows or Linux
Which type of security is easiest/best to use, private SSL, openSSL or shared SSL.

thanks for your help

Shane