Not at all, believe me its not.
An XP 2400 for $137 OEM from Newegg.com is MUCH MORE worth the price than an XP3000 for like $500.
If you have a 2700-2800, youre already almost there and would feel it less.
Remember, 2700xp is NOT 300mhz slower than 3000xp, not nearly. The increase will be minimal.