I've used several ISPs for DNN, some are good some are not.
SeekDotNet can be slow, and their support can be good or very lousy.
JodoHost is good, always upgrading their systems, but a bit slow.
ResellersChoice is quite fast, and they really undersatnd DNN. Also very good support. I'm doing this as a Reseller, and they couldn't do a couple things I wanted, so I moved on.
VorTech is fast, good support, but no ASP.Net 2.0, so I moved on.
3Essentials is quite fast, they help out with DNN, decent support at most times and very good pricing. I keep looking elsewhere, but these guys do it for me. They have ASP.Net 2.0 but no SQL Server 2005. Has not been a problem for me. I've been using them for most of a year - even while trying others.