differentiate transactions in 'projects'

[tereque]

hi,

here is another one....

all of my transactions should be linked to a project they are related 
to. Meaning we have a production for customer XYZ and the project has a 
number (let's say 8170). In the end I would like to have an overview of 
which payments had been moved for this project (incoming payments by 
customer, expenses, etc).

I wonder how I can do this best. I do not really want to set up a tree 
of accounts for each project as I still want to keep my general 
structure of expense accounts('Express costs', 'manufacturing' for 
example). Also I would not know how I could gather 'Income' and 'Expense'

How would I do that best? first thing that comes to mind is using the 
'number' column in each account. Then I could make a search of this and 
have a report of all related transactions. But Maybe there is a better 
way to do this? A 'Job' seems only to gather several Invoices but can 
not applied to any transaction right?
Alo I have not found a way to find all transaction matching a 'number' 
as it seems not workable to include all account in one search operation.