Unable to update windows XP

My internet is doing some strange things, such as it keeps forgetting
the home page I have set and going to "blank page" as my home page. I
think it's also trying to let viruses in because I keep getting pop up
windows about winning a gift certificate from Wal Mart or my system
reg is infected, etc. I believe I'm having problems because my
windows XP is not up to date. I've been trying to update windows XP
(from their website) and keep getting this error message: [Error
number: 0x80072EFF]

When I go into Start - All Programs - Windows Update, it won't even
open up the page to do the update. When I click diagnose problem, I
keep getting a message telling me to: refresh page, check spelling,
or try going to the site from a link (which is not provided). When I
click on the link to "View last diagnostic log," this is what it says:

?xml version="1.0" ?
?xml-stylesheet type='text/xsl' href="xpnetdiag.xsl" ?
xpnetdiag

title
Network Diagnostics for Windows XP
/title
lastRunText
Last diagnostic run time:
/lastRunText
rejectText
REJECT
/rejectText
indeterminateText
INDETERMINATE
/indeterminateText
confirmText
CONFIRM
/confirmText
timeStamp
12/26/10 18:52:46
/timeStamp
component name="HTTP, HTTPS, FTP Diagnostic"
startDiagnosisTime="12/26/10 18:52:46"

rootCause name="HTTP, HTTPS, FTP connectivity"
status="reject"

trace traceType="info" text="HTTP: Successfully connected
to www.microsoft.com."

/trace
trace traceType="info" text="FTP (Passive): Successfully
connected to ftp.microsoft.com."

/trace
trace traceType="info" text="HTTPS: Successfully
connected to www.microsoft.com."

/trace
/rootCause
/component

Any ideas about how I can resolve this and update my windows?
TIA :-)