Advice needed on closed back headphones for an iPod

[Barnaby, Hardly]

Hey there.

This is my first post and a polite request for some advice.

I am looking to purchase some closed back headphones to use with my iPod. I know you guys get asked this question a lot, so I appreciate your patience in humouring me. I have searched on the forums and done some reading-up and now have a good idea of what is out there and what comes recommended. I just have a couple of further questions.

Criteria-wise...

*I have a budget of up to or around £100 and use my iPod regularly in a lot of noisy environments (the tube, buses, trains etc). So I'm looking to block that out without going down the noise-cancelling route.

*I am also conscious of not wanting music to leak and annoy others. So I definitely want a pair of closed-back, over the ear headphones.

*Ideally I don't want something too large/bulky and that is durable enough for me to just stick in my bag when I'm done with them.

So, where does that leave me?

I know the Sennheiser PX200's are highly regarded, but in your experience, do you think they will they block out enough background noise?

If I made the (quite considerable) price jump up to the Sennheiser HD 25-1 II's, am I going to be blown away? I am not an audiophile by any means, but I am going to be using the headphones every day.

Oh, and as a slight aside, is there a huge difference between the HD 25-1 II and the HD 25-SP II?

Is there perhaps anything in between the PX200's and the HD 25-1 II's price-wise that you guys could recommend?

Thank you in advance for your help.

[Barnaby, Hardly]

Anyone?

Sorry to be a pain asking such a common question. Searching on the forums really helped me, I would just love a few final recommendations.