Wish I could be more help. I am still using XP Sp3. However, everything I have heard from people I trust is that Win7 is actually pretty nice and performs well. I do think you are not going to be able to really trouble-shoot well until you can afford more memory. 1Gb is low even for XP. I would say stick with XP until you can afford to upgrade your system.
I know that a friend whois very resistant to change, particularly change that makes it harder to do things the way he likes to do them, boiught a new laptop with Win7 (coming from XP) and loves it. Never has the DNS or IP problems.
The other thing I would ask-- did you go out and buy the software to upgrade an older machine. My personal rule of thumb is I never upgrade M$ OSes. I wait until I buy a new computer with the new OS pre-installed. Have never had an upgrade install other than SPupgrades, go well.