I use Dolphin HD as my browser and love it.
Beautiful widgets is one of the few apps I've laid down money. Very well put together.
I don't use an anti-virus, but I also don't try to download free versions of apps via torrents, open mass forwarded emails and just follow the same common sense rules that I do with my PC. If you find that your computer is prone to viruses due to your surfing/download habits then it's probably not a bad idea to get one for your phone even though the likelyhood of getting one is much much smaller.
Also for customization you might want to check out Multi Picture Live Wallpaper(set a different wallpaper for each home screen) and pick out a home launcher. The big three being Launcher Pro, ADW and Go Launcher. I've tried them all and went with Go Launcher in the end. All three were good, but Go Launcher seemed quicker to me and I liked some of it's options a little better. ADW probably has the most themes though.