It could be a provider cap on downloads. I know i ran into that problem when I tried e-mailing ringtones to my phone. I think Sprint has a cap of 500kb. Not sure about Verizon.
It could be an issuwe w/ empower. I'm able to send and receive pics of 500-800 kb with no problem. Pictures taken with your blackberry using the Large image file setting will be of that size. I've had problems with empower being compatible with the software version on my blackberry. I no longer use it.
Posted from my CrackBerry at wapforums.crackberry.com