I think your idea of moving to 1.0GB to be a good idea. More good ideas at http://forums.cnet.com/5208-10149_102-0.html?forumID=7&threadID=303211&messageID=2824250&tag=forums06;forum-threads
"What is the max RAM supported by XP?"
In your case, Crucial.com and the maximum that your machine can hold is supported. For a longer answer, see google.com and ask this question.
"Can I use a Tv tuner card with this machine?"
I don't know. But I know I use Tv tuner cards from ATI or Hauppauge on many many laptop of less power than what you have.
I have been using a Lenovo laptop for the past 2 years without any problems. It is an Intel Celeron M 420 1.6 Ghz system with 512 Mb RAM, 60Gb HDD, Intel 945 GM Chipset. My needs are very basic .... lots of net surfing, playing DVDs and working on spreadsheets, which the unit still does well. I'm using Windows XP Pro SP 2 on it. I have never formatted the machine but regularly defrag and clean the registry using ccleaner. It has become a bit slow now. I am a bit confused on whether I should get a new laptop with the latest specs or should I increase the RAM to 1 Gb. Could you please suggest , considering my needs what would be the best thing to do? Also advise what is the ammount of RAM I should have on this machine for best performance. What is the max RAM supported by XP? Can I use a Tv tuner card with this machine?