your best way is to get hired by a US company so they can provide you a H1B visa, once you have this visa and after working for 1 year, you can then file for permanent resident card in most cases you can get the resident card within 2 years, sometimes its faster, once you have the resident card you are on the road to becoming a citizen of USA

 

you can then file for permanent resident card

You can't file for a green card in this situation. Your employer files for you.....if they want to.

 

On a slightly different vein, your chances will improve the more work experience you have - especially if you make an effort to get involved in "international" projects and to get to know your colleagues in the US (via phone, e-mail, teleconference, whatever).

Most countries these days have lots of freshly graduated Computer Science grads trying to find jobs, so it's not really worth the employer's time and trouble to try and get someone a visa. A few years out, with some experience (especially some interesting and unique projects) and you become far more interesting and far more worth the hassle to sponsor your visa.
Cheers,
Bev

 

Ah, so it looks like then either work or transferring within a company are my best option.

I do have one question about applying for jobs - how do you know which companies are willing to hire you from the UK (and in turn do the sponsor process)?

Most job adverts don't say whether they will or not (a number do say US Citizens only however) - are there any specialised sites that have job postings from companies in America that are willing to hire internationally... or is that just wishful thinking?

Thanks again for your advice everyone, it's really helpful!

 

Most job adverts don't say whether they will or not (a number do say US Citizens only however) - are there any specialised sites that have job postings from companies in America that are willing to hire internationally... or is that just wishful thinking?

There are sites that (for a fee, of course) will allow you access to a list of job postings reportedly open to those in need of a visa. I would be very wary of these sites. Generally, it costs an employer both money and effort to sponsor a foreigner for employment. Even if a job is posted on a site as being "for foreign applicants" any employer would far rather find someone already in the US with working privileges and no need for either a visa or international relocation.

As far as visas go, the real A ticket has got to be the L visa for an internal transfer. Less hassle for the employer and much greater range of options for the employee. But you have to have worked for the employer for a period of time before you can be transfered on an L visa.
Cheers,
Bev