That folder with the question mark icon means that the MacBook can't find the boot directory. That can either mean it can't find the hard drive or the operating system files on the hard drive are somehow corrupted or damaged.
If you don't have your install disks you can get the 10.4 gray disks by calling AppleCare. 1-800-APL-CARE (1-800-275-2273) They can send them to you for about $16 per disk plus S & H. Just give them your serial number and they'll know which ones you need. With the original disks you also get the iLife that was current when your MacBook was bought included on the #2 disk.
Or if you don't have any files you want to recover from your hard drive you can get Snow Leopard for $29 if you have at least 1gb of RAM and a working DVD drive. http://store.apple.com/us/product/MC573Z/A?mco=MTY3ODQ5OTY You would then erase and reformat your hard drive and install Snow Leopard. You won't need the box set unless you want the latest iLife and iWork. If you only want iPhoto or other single apps you can get them from the App Store in 10.6.6. iPhoto, iMovie and Garage Band for $15 each and Pages, Keynote and Numbers for $20 each.
If you have files you want to recover you can get a larger hard drive and put your old hard drive in an external case. After you install the Mac OS on the new hard drive you can plug in the old hard drive in the external case by the USB connection and try to access it that way.
To buy a hard drive try Newegg.com http://www.newegg.com/Store/SubCategory.aspx?SubCategory=380&name=Laptop-Hard-Dr ives or OWC http://eshop.macsales.com/shop/hard-drives/2.5-Notebook/
Here's instructions on replacing the hard drive http://creativemac.digitalmedianet.com/articles/viewarticle.jsp?id=45088
Here's a cheap SATA external hard drive case on eBay http://cgi.ebay.com/USB-2-5-SATA-HDD-HARD-DRIVE-EXTERNAL-ENCLOSURE-CASE-BOX-/120 636286623?pt=PCC_Drives_Storage_Internal&hash=item1c167ba69f
