Am I being unreasonable?

If you do freelance work, make sure the project isn't so big that you wouldn't be able to finish it before heading out for your already planned trips. Otherwise you'll only hurt your reputation. Most jobs offer 2 weeks of paid vacation time a year with holidays paid off but there's some really progressive companies that do unlimited (within reason obviously) PTO. First starting off you may have to make some sacrifices and lower your expectations a bit. Four weeks of vacation time is a lot a year, it just depends on the employer. Don't be hesitant to start down a great career path. This is the future and it's fun!

That would be too much time off each year in the US paid or unpaid in probably 99% of entry level IT positions outside freelance. In some European countries, they provide all their workers with significantly more vacation time.

Don't just take my word for it Nick: http://theweek.com/articles/463897/americas-war-vacation-by-numbers http://www.bls.gov/news.release/ebs.t05.htm

Or tell your potential employer you value having 4 weeks off a year, and you'll find out yourself if this is reasonable or not. It seems like you're looking for validation from us that what you value is possible and want to challenge people that disagree with the probability being realistic that you can find what you want, but no one will have "the" answer for you. You'll have to see if any employer will let you do that and still retain your job as an entry level IT worker being gone that much every year when you want to go, paid or unpaid.

I can guarantee most places, and not just in IT will not let you leave for 4 weeks each year. If you've ever had a job in customer service, sales, call centers, janitorial staff, and any other minimum wage work they don't offer vacation time at all in some cases, and if they do, you'll rarely if ever find a place that lets you use it. I mention this because the idea of taking that much vacation time isn't something that most positions doing anything will let you do in the US.

In the UK, you would receive a minimum of 4 weeks leave plus bank holidays (normally 8 days) by law all at full pay. All IT jobs I've had have been 5 weeks plus bank holidays.

Yeah, I understand what you're saying about "unpaid time off," but it just doesn't work like that. No US company I've ever worked for has a stated policy about "unpaid time off." I think generally 3-4 weeks off a year is not a crazy demand in most normal office jobs, but I'm not sure about entry-level development. If you feel that strongly about your vacation time, make this clear in your interviews. The worst that can happen is that they'll say no.

I know that this particular question is a few weeks old, however, please allow me to chime in. As Nekilof mentioned, the idea of an employer allowing you to have 4-5 paid/unpaid weeks off in a entry level position is practically unheard of in the work force. In the United States, two weeks are standard and some high level C level managers may be able to negotiate a better deal, but to be honest, I believe it is a bit unrealistic to believe that an employer will hire you with the knowledge that you wish to take 4-5 week long vacations a year.
The only route that sounds doable is working as a freelancer? However, again, the question is, can you have any and all of your projects wrapped up prior to taking said time off?

Well, 2 weeks is something you would definitely be able to find in many companies. However, 3 weeks is generally not something that you see in the multitude of companies for anyone that isn't at a high level position of management. The thing is, most companies will look for a person that they can rely on to be available to do a job or accomplish a task. They become a bit sketchy when individuals are looking for numerous days away from work. Several week long trips a year are a red flag for them.