I am currently developing a software. My main problem is that I have very limited resource, only my PC. So I can't test my software in different version of windows, PC with different configuration.
what can I do to ensure compatibility in different PC's without spending a lot of money.
When you have only your own resources to fund your testing, I find that friends are a great resource :) In the past, if I've built something and want to make sure it works somewhere else, I'll find a friend who has a different setup than I do and send it to them.
The downside is that these folks generally aren't trained software professionals and won't necessarily be able to do proper testing. If I need that, I can simply ask to visit them and use their system for a few hours to so some testing.
Alternatively, you can use the online community to crowd-source your testing and have them find the issues in your software. There are many situations where this isn't possible because you can't release the software into the wild.
Virtual Machines installed on your single PC also allow you to run multiple OS on a single piece of hardware. You can do this with software like VMWare.
Crowd-funding sites like Kickstarter can also be used for you to set specific targets and raise funds to get yourself hardware or VM software that you can use to setup your various environments. You'll need some way to make people want to invest in you, though.
The virtual machine route is probably you best path Here is what you can do:
Also, you can try uTest. This is crowdsourced testing, however there is a fee associated with the test cycle. As far as I know, all the testing is manual.
You can make use of Virtual Machines in which many OS/Browser combinations can be covered like Win XP + FF, Win XP + Chrome, Win 7 + IE etc. Obviously you will need higher configuration for you host machine to run the virtual machines properly.
Also giving the system to novice users for just using them will also help you a lot in finding out the bugs in your system.
You could join a testing community, and ask for their help. Sites like Software Testing Club have weekend events for testers to practice their skills.
If you want to run the tests your self, and you have a little budget, you can try cloud solutions to deploy windows virtual machines of various configurations. Amazon AWS is a good example.
Parallels is another great option. Paid ($100) but well worth it to me. If you value your time at all it quickly pays off. Compared to buying the machines and/or the windows licenses it is cheap so it depends what exactly your resources are.
http://www.parallels.com/
I am a former virtual Box user and for virtual machines on your machine I find Parallels much easier and faster to use. Better at saving state, loading new machines and with less annoyances.
Also it does so many nice things like syncing desktops (if you screen-print to desktop when capturing errors this is very handy!) and setting up your local machine network printers to be available in the virtual machine. Copy and Paste synced, etc. Very handy.
One tip - use snapshots to save the machine once set up initially (after initial tools install). When the trials expire you can rollback a few times.
