Here's the "what to watch out for list" for those great deals from Dell (HP & Compaq).
RAM - must have >768MB for the latest games, 512 doesn't cut it. They may use up all the slots so you can't add your own without replacing theirs.
Graphics - Don't get anything with built in graphics. It can be problematic when upgrading to AGP, even factory upgrades, and you are paying extra for something you won't use.
Graphics II - they screw you royally on graphics card upgrade prices to from the basic systems. They may also sell you cards with uncommon letter designations after the number (like 6800LE, 9800SE, these usually stand for loosers edition or substandard edition). These funny numbered cards are "crippled" from the factory to provide less performance.)
Operating System - They have a special "repair" CD instead of a regular Windows CD. DO NOT LOOSE IT! If you can make a real windows CD from the repair CD do so as soon as you get the system. Make another CD with all the special "Dell only" drivers on it for when the download site no longer supports your PC (in fairness this is more an HP & COmpaq problem than Dell).
Customer Support - Learn the languages and dialects of India. Also learn to tolerate the attitude of Indians towards US customers.
Overclocking - forget it. Most brand name PCs have minimal setup options in Bios to minimize the need for customer support.
Add-in Sound, etc - compatibility may be an issue. The Bios and MB features are stripped down to cut costs. This may create compatibility issues.
Power Supplies - Here Dell has been very good in the past. HP may be undersized for upgrades. Check the current ratings on the 3.3, 5, 12V outputs. The required ratio between the 3 voltage outputs has changed twice in the last 5 years.
Bottom line:
1) You are buying a stripped down machine at rock bottom pricing in the hope you will buy their expensive upgrades and warantees. (Sounds like economy car dealers doesn't it?)
2) They do not expect you, or want you, to try and upgrade yourself so they make it as hard as possibnle. It costs them support dollars and lost profits to make it easy for you. Also, they will try to void the warantee if you do any upgrades. (Just happened to a gaming buddy of mine).
I have several buddies at work who bought "off the shelf" for the low price. They hate to see me coming now because of the imminent "I told you so".
Good luck.