Which is the better phone

iPhone 4

My decision was between these two and I went with the HD7. It isn't about what's "better", it's about what's most suitable for you.

what internal memory does htc come with?

does it have mirco sd slot?

and does it play flash?

It depends on the features that are most important to you in a phone.

Neither phone has expandable memory. Both iOS and WindowsPhone7 are designed to work with the internal phone storage only.

Windows Phone 7 doesn't support Flash and neither does iOS. Apple have said they're not going to support it. Microsoft have said they're not going to support it for now.

If both of those things are important to you, then you'd be better off with an Android phone, but as I say, it really comes down to what you think are the most important features in a phone.

orite well then there both the same to me
i prefer the ipod apps and general layout of iphone then the windows layout
also iphone looks alot smoother and is not as big

Android is the way forward, you can use different sd memory of your choice, you can swap batteries when you choose, applications are launched everyday etc etc.

Windows Phone 7 is new.
They had announced Flash support in one of the upcoming updates.

The HD7 has 16GB memory. But it's really just a Windows Phone version of the Desire HD.
On top of this... The HD7's memory is actually a microSD card. You can take it out and put in a bigger one if you wish, however take note that it might slightly decrease the performance of the phone and it will require a full reset of the phone as it isn't properly supported as of yet.

Here's probably the best advice you're going to get from here:
Go to a phone shop and play around with them for a bit. At the end of the day it's all down to what you want. If you prefer the iPhone then get that. It will also give you a chance to check out other phones as well, like the Nexus S (Android phone that's kept up to date as Google releases updates for Android)

Microsoft have not said they're adding Flash to Windows Phone 7. Andy Lees refused to announce anything about the future roadmap of WP7. Adobe have said Flash is coming to WP7, but until Microsoft confirm it, it's only a rumour.

Microsoft have said they are working with Adobe on bringing flash to WP7. Maybe it will come in the mango update when they upgrade the phone browser to IE9. But on Apple, it's more a case of it will never come.

In My opinion I'd get the HD Desire HD. pretty much the same phone but the OS isn't new and lacking support in some important area's.

As TheBigM said right at the start, it's all about what's better for you. If any of your friends have an iPhone, Android phone or WP7 phone, ask if you can have a play around and what they like/dislike about it. Failing that, go to a phone store and ask them for a run-through - and make sure you make it clear to them that you know they work on commission and don't want to just be pushed towards whichever one gives them the most bonus.

I would say though that getting an iPhone now is a risky business, as there is almost certainly going to be a hardware refresh in June/July, whereas Android and WP7 handsets evolve more organically so you're not going to see such a massive hardware jump in just a few months (at least not one that's going to give you any significantly noticeable performance enhancements for a while).