Is my power supply powerful enough?

So I recently bought the components to build my own PC. This is my first time building a PC, but I wanted to get a good deal and it just seemed to be the best way to go. I asked a friend for help on deciding on which components to buy and also talked with a forum poster on slickdeals. I was trying to stay on a tight budget (less than 1000 including monitor). Both approved of my list, so I made my order.

However, when I told two other people what components I was putting in my computer, they said I should upgrade to a bigger power supply. This would be a huge pain as I already installed the power supply into my case, I have everything sprawled out all over my desk ready to put it together (I don't want to have to wait 3+ days with this stuff sitting out like this), and my dad helped pay for some of the system and I don't want him to think I made an irresponsible decision in what parts to order. So if my power supply is good enough for what I have, then that's good enough for me.

Here are the specs:

Power supply - CORSAIR CMPSU-450VX 450W ATX12V V2.2 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply

Disk drive - Sony Optiarc DVD Burner with LightScribe Black SATA Model AD-7241S-0B LightScribe Support

Processor - AMD Phenom II X4 945 Deneb 3.0GHz 4 x 512KB L2 Cache 6MB L3 Cache Socket AM3 125W Quad-Core Processor

Motherboard - MSI K9A2 CF-F V2 AM2+/AM2 AMD 790X ATX AMD Motherboard

Video card - MSI R4890-T2D1G OC Radeon HD 4890 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - OC Edition

RAM - OCZ Fatal1ty Edition 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory Model OCZ2F10664GK

Hard drive - Seagate Barracuda 7200.12 ST3500418AS 500GB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive

Monitor - ASUS VH226H Black 21.5" 2ms(GTG) HDMI Widescreen LCD Monitor

Case - NZXT Beta Series CS-NT-BETA-B Black Steel / Plastic ATX Mid Tower Computer Case

Extra fan - 120mm Antec Tricool LED fan

I don't plan on overclocking or anything. At most, I'll add an extra hard drive down the road.

So is my power supply good enough to run this system? And how much more could I add to this system down the road without needing a new power supply?

Is it really worth the time and extra money sending the power supply back?

Alright, because I was getting really worried. Quite a few people said I should upgrade, but I'm very reluctant. I spent A LOT of time on trying to find a computer to buy, and I really don't want to have to wait all that time to send something back. Plus, I'd feel really guilty for buying a weak power supply in the first place and having to spend more money.