Here's a quick summary:
WPA was designed to be a stopgap measure. WPA uses RC4 encryption.
WPA2 uses AES for encryption. It is therotically stronger than the RC4 encryption, but AES requires more encryption churning horsepower to do the encryption/decryption, and therefore needs more modern hardware.
If you're using a 63-character long, random passphrase, you're doing pretty good. WPA2 IS better, no question, as WPA2 is not breakable (under current theory), while WPA is breakable (again under current theory). However, 63 random characters starts to get into the area where someone would quite literally need years to crack the passphrase.