I'm currently getting some components and tooling together for one of my 360 CPs and I would like a little help/advice with the artwork for it if possible.
This is a forum friendly image that I would like to use for my 1st CP:

What I would like to do is extend the suns rays so that the image is something more like a 3:2 ratio (12"x8" - ~305x302mm).
This is a rough idea of what it would look like (paint skillz ahoy!):

Whilst I would love it if someone could do this for me I would also like to know exactly how it would be done. I have no art program knowledge at all and I guess this would be as good a time as any to start to learn.
What program(s) would you use and what would be the process that you would follow?
I have a slightly higher resolution of the image that I will attach to this post. Would this image be high enough resolution or would it look a little grainy? I guess (and I'm only guessing here) that it would be a better idea to vectorise the image? I had a play with vector magic but it didn't quite give an accurate result.
Is there a free program that I could use to vectorise the image by 'hand'? I realise you can use illustrator for this but I seem to remember there is a free program that does a similar job. Saying that I may be thinking about a program that is similar to Photoshop rather than Illustrator.
Would it be best to vectorise it and then extend the rays or vice versa?
Thanks in advance for any help

[Edit: I've just been having a search and I think Inkscape may have been the program I was thinking of, would it be up to the job?]