Is 500 watts enough

The Antec TP500 is plenty for your config.

Hi newcomer and welcome to the Tom's hardware forum.

This are the system requirements for the 5770

ATI Radeon™ HD 5770 System Requirements

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
450 Watt or greater power supply with one 75W 6-pin PCI Express® power connectors recommended (600 Watt and two 6-pin connectors for ATI CrossFireX™ technology in dual mode)
Certified power supplies are recommended. Refer to http://ati.amd.com/certifiedPSU for a list of Certified products
Minimum 1GB of system memory
Installation software requires CD-ROM drive
DVD playback requires DVD drive
Blu-ray™ playback requires Blu-ray drive
For an ATI CrossFireX™ system, a second ATI Radeon™ HD 5770 graphics card, an ATI CrossFireX Ready motherboard and one ATI CrossFireX Bridge Interconnect cable per graphics card (included) are required

The recommended PSU is for the entire system, so, with ur current PSU is enough. BUT if u want add another GPU for Crossfire in the future, u need upgrade the PSU.

Actually that 500 watt Antec unit would be able to power 2 5770s it would be bringing it up to its limit but could do. ATI recommends 600 watts for 5770 crossfire but they over estimate the requirements due to the amount of cheap PSU's floating around so even if he did decide to put a second 5770 it would most likely run it without a problem.

At full load a 5770 will use around 100 watts so times 2 thats 200 watts, I5 750 max out at 95 watts 2 hard drives at about 8 watts each so thats another 16 watts and a DVD Burner thats about another 25-30 watts and a few fans I will give that another 10 watts thats over estimated but I will give it 10..

So...
200+95+16+30+10=351 watts hmm sounds like plenty of power to me. Add another 50-75 watts for RAM and motherboard and still have plenty of power

yes you will be fine!

Im thinking of ordering a pc from cyberpower, specs:
Case: CoolerMaster Silencio RC-551 Mid-Tower Silent Gaming Case Black featured front USB 3, Internal sound damping. [+17]
Freebies: None
Lights & Illumination: NONE
Extra Case Fan Upgrade: Maximum Case Cooling Fans for your selected case [+10]
Cyberpower Noise Reduction Technology: None
CPU: AMD A8-3870K 3.00 GHz Quad-Core APU w/ Integrated Radeon HD 6550D [+9]
Overclocking Service: No Overclocking
Cooling Fan: Asetek 510LC / Xtremegear Liquid Cooling system w/ 120mm Radiator (Asetek CPU Water Cooling ***Overclockable XXX***)
Coolant for Cyberpower Advance WaterCooling Kits: NONE
Motherboard: Asus F1A75-M Pro AMD A75 Chipset CrossFire supported DDR3 Socket FM1 Micro ATX mainboard w/ 4 RAM slots, UEFI Bios, 7.1 HD Audio, GbLAN, HDMI, USB3.0, SATA-III RAID, 2 Gen2 PCIe X16, 1 PCIe X1 & 1 PCI ***Overclockable XXX*** [+8]
Internal USB/SATA Expansion Module: NONE
Memory: 8GB (2x4GB) PC10666 DDR3/1333mhz Dual Channel Memory [+24] (Kingston Value Brand)
Video Card: None, or On-Board Integrated Graphics
Freebies: None
Dongles: NONE
Video Card 2: None, or On-Board Integrated Graphics
Video Card 3: None, or On-Board Integrated Graphics
Power Supply Upgrade: 500 Watts Power Supplies [+10] (CyberPower 500W Gaming Power Supply (No Overclocking recommended))
Hard Drive: 500GB SATA-II 3.0Gb/s 16MB Cache HDD (Single Hard Drive)
Data Hard Drive: NONE
Hard Drive Cooler: Vigor iSURF II Hard Disk Drive Cooling System [+15] (1 x System)
External Hard Drive (USB 3.0/2.0/eSATA): None
USB Flash Drive: None
Optical Drive: 24X Double Layer Dual Format DVD±R/±RW + CD-R/RW DRIVE. (BLACK COLOR)
Optical Drive 2: NONE
Sound: HIGH DEFINITION ON-BOARD 7.1 AUDIO
Operating System: Microsoft® Windows® 7 Home Premium [+74] (64-bit Edition)
Network: ONBOARD 10/1000 NETWORK CARD

Will the selected components (specifically the 500watt psu) be compatible, and good enough for gaming and youtube? Thanks
-Price: £565.20 inc. VAT