I have a HTC Hero with a 8GB card, thats more than enough to store 2000 MP3's and countless photo's. You can get a 16 GB card for it if you need more memory.
I'm very pleased with the phone, I've had BlackBerry's for a couple of years, and good as they were, the HTC is far superior and has a much larger screen. I did a lot of research before i bought it, and am very pleased I didnt follow the crowds and get an i-phone.
I am very impressed with it's capabilities and use it regularly for Yahoo IM (via E-Buddy), Google Talk, Skype Lite and Facebook. If you can connect to open wireless the internet connection is pretty fast and the screen is large enough to browse the web.
The only drawbacks of the HTC are:
1. The camera doesnt have a flash, so you can't use it at night
2. the touch screen takes a bit of getting used to, and be prepared to call people you don't want to speak to until you get used to it.
Hoep this helps you to decide?