As always ....will I have enough power?

Hello:

I have the following and was looking to upgrade my GPU to Radeon X1950 from X700pro. will I have enough power at 500 watts? I used that wattage calculator from the sticky page and it said around 425watts.

CAS: X-BLADE II Mid-Tower 450W Watt w/ Side-Panel Window COLOR)
CPU: (939-pin) AMD ATHLON64 X2 3800 CPU w/ HyperTransport Technology
CD: LG GWA-4161 16X DVD+/-R/+/-RW + CD-R/RW DRIVE DUAL
CD2: NONE
FAN: AMD ATHLON64 CERTIFIED CPU FAN & HEATSINK + 3 EXTRA CASE
FLOPPY: NONE
HDD: 200GB Hard Drive [+36] (SATA150 - Maxtor 200GB 7200RPM 8MB Cache
Hard Drive)
KEYBOARD: PS2 MULTIMEDIA INTERNET CONTROL KEYBOARD
MOUSE: Logitech Optical Wheel Mouse
MODEM: NONE
MOTHERBOARD: (Sckt939)EVGA nForce4 SLI Chipset SATA RAID Dual PCI-E
Mainboard w/GbLAN,USB2.0,&7.1Audio
MEMORY: 2048 MB (512MBx4) PC3200 400MHz Dual Channel DDR MEMORY
(Corsair Value Select)
NETWORK: ONBOARD 10/100 NETWORK CARD
OS: Microsoft(R) Windows(R) XP Home Edition
POWERSUPPLY: Super Alien 500 Watt See Through Power Supply w/ Fan Speed Control
SOUND: ESS 3D WAVETABLE SOUND PCI
USB: Build-in USB 2.0 Ports
Video: Radeon X700Pro

Thank you!