QuickBooks can convert data from other Intuit products, such as Quicken, as well as from some other non-Intuit accounting products, like Peachtree Accounting.
If you've been using another financial software product and you'd like to import information from that product into QuickBooks, you can do so if the product allows you to export to a spreadsheet or text file. You can import lists that correspond to QuickBooks lists, budgets, and individual transactions.
Converting to QuickBooks from Quicken
Converting to QuickBooks from Peachtree
Reference Guide to Import Files
Creating an import file
Importing transactions to QuickBooks