your system is close to mine. I have a 300w inverter and a 300w PS. Running XP Pro on an AMD XP 2000 on a MSD Raid board. I also use a 7200rpm 80gig drive and full size dvd. ATI 8500 DV All in Wonder card, 802.11b wireless and a data chute pcmcia card adapter. I have no power problems with this setup.
As far as the Lilliput: can you afford to replace the "TV" monitor if you don't like it? If not, you should spend the extra up front and get what you think is ther better option. Remember, with a 7" screen, the problem is not with the looking at the front end software, or the pretty icons. The problem with the cheap monitors arises when you have to read the little Windows error messages, reload your machine, install software, etc.... All that text is very small. Its bad enough with the "better" monitors when you have 41 year old eyes.