need advice about querying/export 300.000 rows

[RS_Arm]

Hello guys
I need to export bill/receipt from my database to text files/xml.
My database has about 300.000 lines for bill/receipts.
Should I export all lines in one single processing, or should I export one bill by one?

My database is based on Access2 and I'm doing this with VB6.

Thank you in advance for your advice.

[Hack]

After the export, what will be done?

Will the bills be mailed to customers? If so, then one by one would be the way to go.

[RS_Arm]

Each bill will have one file per department.
Those files are needed due to integration matters.
What worries me more is how the server will handle and manage such amount of data.
This operation doesn't need to very quick, (kinda 5/10m), it can be processed over 2 or 3 hours.
What I need is to optimize the querys, so that the server will not be overloaded of data and get stuck.