Is a Data Access Plan of 200MB/month enough for surfing 2-4 hours per day on the Nokia N800? Anyone have there own expereinces to share? Also, is there any way to track the total amount used during the month?

It depends on what you intend to be surfing - plain web pages, youtube-type videos or streaming-audio. My initial reaction would be that it won't be sufficient over the course of a full month, assuming you use it every day of the month.

200MB/30 days => 6.66MB/day

Given the above figures, you will remain within your 200MB data plan unless you exceed 6.66MB/day on average (and the data plan may consider this TOTAL bandwidth, ie. both upload and download contribute towards 200MB). I'd say it would be very easy to exceed your daily quota if you hit just a few media rich web sites on a daily basis.

Turn off the image loading in Opera and you're a long way already
I read the Palm version of Slashdot most days through GPRS, and one day's worth of /. takes only about 50-100k. I keep images off (or only already retrieved images) too, just in case I go off-site following the occasional link. And I use privoxy as well, to be sure. And I keep a browser window with gmail permanently up and running (it doesn't matter if you change network between wi-fi or bt now and then), this makes it possible to check mail with only a few tens of kbytes as well. All very useful when using GPRS without a data plan (i.e. I have to pay as I go). And it makes GPRS fast enough too..

So no downloading full movies or even mp3's... and perhaps even turning off all pics if desperate to surf but running out of data... I am so nervous to go over $200MB cuz it is $5/MB after that... 300MB total/month = $500 extra/month. Ridiculous!!! I am going to aim for 175MB for my 1st month. I sure wish I had a data tracker for my bluetooth connection with my phone.

Well, at least you can monitor the amount of networking data on your N800, as long as you're connected (in tools/ somewhere), but that's only as long as you're connected -- it gets reset in between.

I know that is how I am doing it the past few days... adding up the totals from each connection... but by the end of the month it will be a really rough estimate i am sure.