Many people around this time are upgrading computers and such. Most of them I observe are getting cheated easily by the vendors using Microsoft Windows Vista and other latest software releases as the bait.

I just thought I could help you all by listing here in short what to look for when you want to purchase a "Windows Vista Ready" computer.

1. Intel Pentium D (Dual core) and Intel Core2Duo are not the same. I had to send back three of my friends to their dealers who had tricked them into buying the "latest dual core processor" Pentium D.
2. Go in for a good processor. Start with the entry-mid range and look for the "big leap" as I call it. A "big leap" occurs when the cost of the next best model in the same item class is significantly more than the current model. Say, by a thousand rupees more. This is when you stop looking for the next best model unless the benefit from the next best model is significantly more. Significantly. Come on, can't let all the trade secrets out, can we?
3. After the processor is settled, get in a nice bit of RAM. 1 GB ought to do for most people even today. Those who expect a lot - yes a LOT - of multitasking should go for 2 GB or RAM. Common 2 GB RAM scenarios include: Windows Development, Graphics Design, Audio Engineering, Gaming, etc.
4. The manufacturer (brand) of the RAM module doesn't matter if you don't know to tweak it (commonly known as overclocking). Just make sure it is the fastest of its type. DDR SDRAM (DDR1 now) tops at 400Mhz, DDR2 SDRAM (DDR2) tops at 833Mhz in most places. Even higher in some.
5. Talking about speed of RAM, make sure your motherboard supports your RAM and at the same speeds. Also, check if your processor's "bus speed" is supported. The higher the bus speed of the process, the better the performance. Also look out for more cache in your L2 and L3 of the processor.
6. Your motherboard is very critical to the overall performance of all these independent components. Make sure you get a nice board with as few fancy features as possible. In general, pick one that keeps out a heavy on-board video accelerator, high sound stuff (like a 7.1 or something). We can add the graphics card separately - which is both better performing and offers a higher value for your money.
7. The graphics card can be anything from the 6xxx series to 8xxx series from nVidia. Or any of the X series from ATi. The only thing to watch out for are the cards that are specially modded. Some cards from nVidia come as the LE variant - which is literally a "limited edition". Go for pure cards or the heavy, top-end varieties in the lower range. For example, if you can buy a top-of-the-line 6xxx series in nVidia instead of a entry-mid range 7xxx series, go for the top-of-the-line 6xxx series unless you know what you are doing.
8. Now the hard disk. This piece of hardware is the major limiting factor for your computer. This and RAM are actually the ones that control the speed of your computer like a wall-fan regulator. Better the hard disk, the faster your computer runs overall - right from boot time to shut down.
9. Optical drives are all pretty much the same. Just ask your friends around for the drives and the media they use to write on them. If that combo suits nice, just go ahead and pick it. You would be surprised when you have a look at the number of manufacturers who have sprung up these days.
10. Just pick a nice cabinet you would like on your table. These guys take care of ensuring that most cabinets are well ventilated, so we can just sit back and pick one. Just go in for a higher model of SMPS if you buy a high-end graphics card.

More on this later, looking at posting this differently as well. Hope it helps.