Windows XP only used to be able to use 1.5 GB, but that was fixed in an update after SP1 (not SP2), which fixed the whole 100GB hard drive issue (XP used to not be able to use more that 100GB on a HDD). And as for is it needed, unless you are doing some CGI or major audio or video editing... no. In about 2 years, I'd say that would be a possible neccessity or worth it, but definitely not now...