Here a few point on linux.:
1 you wont need to do a defrag. Well you can do it but its pretty much useless....
2 Dont worry too much about virusses. You can get an anti-virus but unless you connect directly to a win network, dont worry too much about it
3 SpyWare. I dont know any that affect linux so dont worry about it.
If you have'nt, find you way around in a virtual terminal (like Konsole, xterm, etc....) the vt's are from my point of view what really make linux an amazing OPSYS.
and here is a good links.: