I have an EnV, and I subscribe to Vcast to get unlimited internet, Vcast access, and Get it Now! for $15/month.
If you don’t mind using your minutes while you’re online, there is a $5/month plan for that too.

On my phone the connection is really pretty fast, as long as the webpage doesn’t have too many graphics. A lot of services have special pages made specifically for mobile access- like Gmail and facebook load very quickly are are very easy to navigate.

If you are looking for the broadband card, I don’t personally use it, but I attached some links from Verizon’s website as well as another Y!A question on this topic with a good answer below. There’s even a place where you can "test drive" it, so maybe it will give you a feel of how fast it is? Not sure how that works. But it looks like they are charging $79/month for the unlimited access plan, which is the only one I see available.

Good luck!
References :
http://support.vzw.com/features/data_services/broadband_national_access.html
http://www.verizonwireless.com/b2c/store/controller?item=planFirst&action=viewPlanList&sortOption=priceSort&typeId=5&subTypeId=13&catId=409
http://answers.yahoo.com/question/index;_ylt=ApIWkkcXLGTXyPriMXP9qkAjzKIX?qid=20070328212236AAThvQv

Go to the VZW link and get started with their voice/data packages.
References :
http://www.verizonwireless.com/b2c/store/controller?item=planFirst&action=viewPlanOverview&catType=voiceData&cm_re=Global-_-Plans-_-Voice%20%26%20Data%20Plans