Depends on what kind of photography you want to do.
The kit lens is not a bad general walkabout lens but if you go for walk in the woods and want to photograph a squirrel, the 55-250mm IS lens is perfect for this.
I managed to follow one up a tree and photographed it while it sat eating.
Depending on how 'snap happy' you are, I would also suggest a minimum of 2 x 4GB SD HC cards.
Don't buy the cheapest you can find, go for 'HC 6' cards as they will write to more quickly and help with buffering if you take continous shots.
A lot will depend on what you plan on doing.
For a general walkabout day the need is different to going on a 2 week holiday to somewhere that is going to be bright and sunny and full of potential landscape shots.
I generally take the bare minimum of walkabout kit that I take on holiday.
So this would include 2 lenses, hoods and CPL filters (depending on the weather), a couple of SC cards and a spare battery.
Obviously this is a longterm plan, after forking out for the 450D I wouldn't expect you rush out and rack up the credit card

Oh and as regard to getting home.
A card reader, a decent spec PC (you'll eventually get into processing your pics via software), a woman with patience as your demand for coffee increases as you process your pics
Obviously this is a longterm plan, after forking out for the 450D I wouldn't expect you rush out and rack up the credit card
