Tried to post earlier but the site was down so might be repeating other posts now!
You can get brand new ACA1232/33 it's quite up to the task of running OS3.9 as you can see in my Video here:
http://www.youtube.com/watch?feature=player_embedded&v=pOWoLD94ZqgI'm also using an Indivison AGA MkII. My CF card is now 8gb, plenty of space for me, you can of course use 32gb, you can make your own custom Rom with updated scsi.device and BoingBag patches which you can load from image using the ACA's Maprom function.
As you want to run OS3.9 don't bother with plain Ram upgrades or 020/ram accelerators, you wont be satisfied with the results.
If you have the funds and want the best experience then the Blizzard 1260 would be the card of choice, be prepared to pay top dollar in the current market though.
I wouldn't bother with the 040 cards in an A1200 for me it's not enough speed vs the 1230 (IMHO) and the prices have gone quite high, you might as well save extra for the 1260 or enjoy the 1230
Networking is fun but not very useful for web browsing. I use FTP & Wookiechat(IRC Client) mostly on my Amiga's and only open my web browser to grab files from Aminet.