I hope someone can answer my basic questions....

What is a header checksum?
Is the XP firewall and Remote Assistant safe?
Is it possible to change the date/time a file is accessed after accessing it (windows or linux)?

When attempting to compile my program the thought crossed my mind that maybe something isn't in my search path. How do I do that?

I've been reading a book on TCP/IP. How crucial is it to learn the sizes of each part of an IP header and so forth?

Is VB good for anything? I know COBOL isn't.