I want to upgrade my Dell PC which is about 4 years old. Everything inside the tower. I'm concerned that everything may not work well together.
I plan on replacing the PCU, Motherboard, Video card, Hard Drive, DVD Burner and Memory. Any help on finding the right parts so that all works well would be helpful.
I was hoping to spend around $700 to $800.

Thanks

With a budget of $700.00 to $800.00 why not just purchase a new computer?

Bear has a good point - brand new PCs (with valuable warranties!) cost less than your budget. The UK Dell web site always has special offers of one kind or another - I assume that the US Dell site is the same: http://www.Dell.com. New Dell PCs are still great but are now priced much more competitively than they used to be - they're hard to beat these days.

If you really want to upgrade your old system, then you will probably need a new system case, or at least a new power supply, in order to support a Pentium 4 motherboard and processor and give the system enough power if you are planning on fitting a lot more memory or a powerful graphics card.

To be able to give you detailed advice, you need to have some idea of what you want to buy already. There are literally thousands of products out there so it's hard for us to make a general statement about compatibility if we aren't sure what you want to buy.

But here goes .....

DVD-Writer or DVD-ReWriter - no issues if you get an IDE drive and have a motherboard with an IDE slot for the cable to plug into. Note that IDE cables are normally sold separately.

Memory - no issues usually as long as you buy the same type and speed that is supported by your motherboard, e.g. DDR or DDR2 RAM.

CPU - no issues if you buy a model that is supported by your motherboard. As long as your not going for one of the fastest processors on the market, any new motherboard is likely to support any new processor that you buy ASSUMING that it's the same socket type, e.g. socket 775. If it isn't, then the processor simply won't fit into the socket on the motherboard.

Video card - no issues normally as long as you get the right slot type, e.g. AGP or PCI-Express (PCI-X). Note that PCI-X graphics cards tend to use a 16-speed PCI-X slot, not a 1-speed slot.

Hard drive - almost anything goes as long as it's the correct interface - Serial ATA is now the most common standard rather than IDE.

Motherboard - get one with a CPU socket that matches the CPU you want to fit and make sure that it has the features you want, e.g. on-board sound. If you're new to this, pay a little extra to get a better brand such as Intel or Gigabyte - they are easier to set up and come with a good manual. Also, make sure that it's the right size to fit your case! ATX is the easiest to work on as it's full-size, mini-ATX can be fitted into a smaller case but you get fewer expansion slots and everything packed in a bit more tightly, BTX is a new format that has been released this year and requires a specific BTX-compatible case.

Hope that helps