ecommerce package?

hi folks.

a client wants a full blown catalog on their site. this obviously means a catalog of products, ability to 'open an account' and then re-order previous orders, the ability to send a gift package to recipients etc...

in addition the above, they also need the ability for 4 different clearance levels:
1) the user him/herself: they can make orders, edit and delete their own orders
2) operators: who can log in, and make orders for customers and take payment. they can edit and cancel customers' orders too.
3) proccessors - the folks who make shipment. all they need to do is view the order and to check it off when completed.
4) the super admin, who can do anything and everything.

my host has OScommerce installed as an option, but unfortunately i havent had a chance to look at it properly and see what it can or cant do.
i'm also not as proficient with php as i am with asp, so making mods on the cart would not be so smooth for me.

can some one who knows OSC tell me how it compares to the above general requirements? can it handle it?
also: are there other products that can handle this?

i am sure i can develop something like this on my own in ASP, but why re-invent the wheel if something is available already, right?

anyway, all feedback would be appreciated.
thanks in advance!
Sn