Need Help Building a PC

im trying to build a very basic pc for my brother. just enough to play mp3's, online access, and some games, im not sure if i have every part. here is a list of what i have.(havnt bought them yet, in my wish list on newegg.com)

1.Motherboard
2.Video Card
3.Sound Card
4.CD/DVD Drive
5.80 GB HDD
6.Intel CPU

Can you tell me if i am missing anything?

 

Memory
Case
Power supply (May come with case)
Floppy disk drive (Not used much anymore but for the sake of £5 it would be silly not to get one.)
Monitor
Keyboard/mouse
Speakers

 

can you recommend a good power supply, and are they easy to install?

 

I would recommend buying a case with the PSU (power supply) already fitted if you are not very confident about fitting one. However, with that said it is not hard to fit one. Here is a little guide - http://www.buildyourown.org.uk/pc_building/fitting/pc_case/
As for what PSU to buy, generally the best you can afford is the way to go. Get at least 400w and go for a well known name such as antec or chieftec. Alot of people scrimp on their power supplies and it comes back to haunt them further down the line.
Something like this should suit you fine - http://www.overclock.co.uk/customer/product.php?productid=16250

 

I would go with a motherbaord that has a vga slot, if tryin to play games I would not go with an intel celeron. I would go with a amd, beause they are cheaper than the intel and perform better overall. With that in mind shop around for a barebones kit, if the case style and looks are not very important. Don't be in a rush to buy everything, do research on the part you are thinking about buying. Go to froogle.com and see if u can find that certain part cheaper. If u are looking at the cases by themself, i would makesure that it come with 400w or plus powersupply also look at the styles of motherboards it takes. example:atx,matx. The only parts I would order off the internet is the case and powersupply together, the motherboard, and processor, and some ram. Everything else u can find at your local department or radioshack.
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1592094&CatId=1279