Hi,
Firstly 2 beeps indicates a system board problem, nothing specific is mentioned.
Have you tried turning it on with the power adapter connected and switched ON?
If so and it works you ''may'' have a battery problem.
If it doesn't, try the following:
Disconnect the AC power adapter, then remove the battery pack (Section 5-5 in the attached link) and finally ''reseat'' (i.e remove and reinstall) the memory module(s), (Section 5-10 in the attached link).
http://www.hp.com/ctg/Manual/c00444244.pdf
Reinstall the battery pack, connect the AC power adapter and see if it comes on.
If not, unfortunately you have a problem with the motherboard. here is a link on how to remove the motherboard.
[guide|12169]
You can go online and find replacement motherboards (check your motherboard version) but given that the PC was released 10 years ago it may not be worthwhile fixing and you may be better off buying a new replacement PC.
To retrieve your data just Google "how to get data off the hard drive in a dead PC"