PHP isn't a just UNIX technology - it's been built for both Windows and Linux. So you can quite happily get PHP running on your machine.
As for the question, is PHP easy to learn? Well I found it easy to pick up but I had been programming for a few years before this. It's also similar to other languages I have used. But I would still say it is pretty easy for somebody to pick it up. All the commands are very close to English (e.g. mysql_connect() to open a database, strcmp() to compare two strings). Here are some good sites to help you learn PHP with tutorials etc.
PHP Freaks - A personal favourite of mine. Lots of useful tutorials and an extremely active forum to ask questions in.
Dev Shed's PHP Area - The articles here ar eprobably a bit more advanced than what a beginner would need but the site is still worth a mention. Also has a fantastic forum for getting your questions answered.
PHP Resource Index - Index of various tutorials, articles, code snippets etc.
W3School's PHP Area - W3Schools is always a great place for beginners. Well worth a look.
Not to mention your local library/bookstore is bound to have a lot of books on PHP.
The best way to learn PHP is to get it working on your Windows machine. That would mean downloading and installing Apache (a web server), PHP & MySQL (a database) then getting them all working together. Now that sounds like a pain but luckily it isn't (hurrah!). You can download things called WAMP packages. WAMP stands for
Windows
Apache
MySQL and
PHP. it basically will install all three for you in one go. The WAMP package that I use can be found
here.
So if you do start to learn a little PHP (and I do recommend it for creating an online store - to access a DB containing your products), feel free to post questions here and we should be able to answer them for you.