Can I install SSD on a MacBook white mid 2007?

Yes, you can. Most all SSD's are the same size as notebook hard drives. Just confirm that the SSD you're considering height is the same as the current hard drive. Most are 9.5mm.

Check the link speed your MacBook will support. Click the apple on the left of the menu bar, then about this mac, then more info, then system report, then serial-ATA. If the link speed is 3 GB/s that is SATA II. If the link speed is 1.5 GB/s, that is SATA I. There aren't too many SATA I SSD drives around, most are SATA II or SATA III.

I installed an SATA III SSD in my 2010 mac mini (with OS X 10.7 Lion), and it ran at SATA I speeds. After consultation with the seller, they said to use their SATA II SSD, so we switched, and it runs fine at SATA II speeds. SSD's are supposed to be backwards-compatible, however, that doesn't always work so well.

PS. I use and recommend SSDs sold by OWC.