Don't forget, you can not "over power" your system with an upgraded PSU. For example, if you require a minimum of 300 watts PSU, then you should buy something bigger..maybe 430 or more watts. This way you have room to add components in the future.
Also...you get what you pay for with PSU's...don't go cheap. Buy well known, brand name units with good reviews.
CPU - P4 2.4C, 800FSB W/HT - CONSERVATIVELY OC\'ED
MOBO - GIGABYTE GA-8KNXP 2.0 875P CHIPSET/DUAL BIOS VER. FE
RAM - 1GB (2X512) OCZ PC3200 REV 2, 400MHZ 2-3-3 6
VID CARD - ASUS RADEON 9600XT 128MB W/VIVO
FLOPPY - SAMSUNG 1.44M
HDD - MAXTOR 120GB 7200RPM ATA133 EIDE W/8MB BUFFER
DVD - LG GDR8162B 16X IDE DVD ROM
PSU - ENERMAX EG465P-VE FC 460 WATT
VANTEC VP4-C7040 AEROFLOW HS/FAN
5 X VANTEC STEALTH 80MM CASE FANS