Upgrade oscommerce web store to Magneto best solution

I have been looking at upgrading my Oscommerce webstore to the much hailed Magento.

What would my best option be for upgrading?
I wish to keep the existing domain whilst testing and tweeking the new webstore, is it best to have a seperate test domain?

Once i am happy i would like to be able to import the existing customers to my new webstore and make it live replacing the old webstore..

I am after some advise on the easiest way to go about the change over.

I am sure someone must have been through this process and has some tips.

 

Use Google with "Cart2Cart" keyword. Those guys are the best in shopping cart migration.

 

Thanks grut thats 1 issue resolved.
I think 1 solution could be install magento in folder oldstore.com/store

test it, try to find a nice template, populate with products, import the customer accounts and orders/

Then 301 redirect oldsite.com to oldsite.com/store
and obviously do the same with any old urls that have decent serps.

Hopefully the drop in the serps should be reduced to a few weeks.

I see there are loads of paid extensions what would everyone recomend as the top extensions that will increase my conversions/sales?

 

Magento doesn't need any extentions, imho.
I think new quality backlinks might increase your sales.