replace 30A with 40A fuse?

You can get these at the local auto parts store. It's the Green or the Red plastic box with a small copper wire in it that you can look through the clear plastic to see the fuse. They sell for about $4.99 up here in Canada.

cool, thanks guys.  yea, it's the green box-type one.  I couldn't pull it from the fuse box, but then I realized

there was a screw above it and one below it.  So I guess I have to unscrew them first, and then pull the fuse?

(Of course this blew right before I had to go on a 90 minute drive in the 90+ degree weather....no A/C or radio!  AGGHH!)

Yes, you have to take the two phillips screws out and pull the entire piece out ( The green box and the two copper angle pieces ) and bring it to the parts department and ask them for one and show them the fuse otherwise they won't know what your talking about.

(....learning, learning, learning...)

ok, so I bought the 40A fuse from Strauss Auto ($2.50).

Brough it over to my car, screwed in the bottom screw...ok.

after all that blabbering, my question is, are you always safe from blowing

You are safe if you disconnect the battery from the car when replacing fuses..but if there is a short somewhere, when you re-connect the battery then you might have some problems.  Also, its usual for the battery terminals to spark when re-connecting the power wires.  Little stuff like the radio, alarm, and ect. draw power even when the car is off..which in return gives you the sparks.