External device issues

I recently put together my own computer..installed xp pro on it and updated it and all the drivers. It works great, but theres a strange issue with my external hard drive. It's a western digital mybook usb drive. If I connect it after windows has begun, it freezes my computer and I can't do anything but restart it. If I connected it before windows begins, it goes to a black screen and won't even start. If I plug it in right before the desktop comes up, it works perfectly fine. I've tried it on my laptop and it connects and loads the files instantly. I'm also having somewhat of a difficult time with my cd rom drive. It reads discs...but very very slowly. I've contacted both the technical support for the cd rom and for the motherboard, and both sources said to update the drivers...but I did, and I'm still having the same problem.

Well it's a 600W power supply, i don't know if it'll help but heres a list of all the parts I got for it..

OCZ ModXStream Pro OCZ600MXSP 600W ATX12V V2.2 / EPS12V SLI Certified CrossFire Ready 80 PLUS Certified Modular Active PFC Power Supply compatible with core i7 - Retail
http://www.newegg.com/Product/Prod [...] 6817341017

LITE-ON Black 22X DVD+R IDE 22X DVD Writer LightScribe Support - Retail
http://www.newegg.com/Product/Prod [...] 6827106328

Western Digital Caviar Black WD6401AALS 640GB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM
http://www.newegg.com/Product/Prod [...] 6822136319

ARCTIC COOLING Freezer 7 Pro 92mm CPU Cooler - Retail
http://www.newegg.com/Product/Prod [...] 6835186134

SAPPHIRE 100265HDMI Radeon HD 4830 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Prod [...] 6814102822

Intel Core 2 Duo E7400 Wolfdale 2.8GHz 3MB L2 Cache LGA 775 65W Dual-Core Processor - Retail
http://www.newegg.com/Product/Prod [...] 6819115206

ENCORE ENLWI-N IEEE 802.11b/g, IEEE 802.11n Draft 2.0 PCI 2.3 Wireless Adapter Up to 300Mbps Data Rates 64/128-bits WEP Encryption WPA, WPA2 WPA-PSK, WPA2-PSK - Retail
http://www.newegg.com/Product/Prod [...] 6833180052

G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ - Retail
http://www.newegg.com/Product/Prod [...] 6820231122

NZXT Alpha Black Steel ATX Mid Tower Computer Case with Open Window - Retail
http://www.newegg.com/Product/Prod [...] 6811146041

GIGABYTE GA-EP45-UD3R LGA 775 Intel P45 ATX Intel Motherboard - Retail
http://www.newegg.com/Product/Prod [...] 6813128359

I could try using another power source from my parents computer, but I don't think my dad would agree with that idea...it seems the 600W should be good enough unless it's faulty though..