I am wondering why some sites like www.jdpoweronline.com will not load when using XP on dialup with the latest firefox compared to windows 8 on high speed with internet explore it works it MUST be mostly because of dialup I think any thoughts?Dial up has a max of 56 kbps **
DSL is often 1 1000 kbps  ** pr better.
DSL is often by AT&T
Broadband data rates are presently in the Mega bits per second.
Comcast is a popular Broadband service in the USA

** Here 'kbps' means kilo bits per second.

Some web site MAY have simplified HTML pages and low RESOLUTION graphics to help improve apparent speed.
I found instructions to use tracert the results are as follows, but do not know how to interpet:

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\Owner>tracert www.jdpoweronline.com

Tracing route to www.jdpoweronline.com [54.241.157.81]
over a maximum of 30 hops:

  1   448 ms   452 ms   437 ms  ipt-ntca01.dial.aol.com [207.200.122.1]
  2   437 ms   452 ms   452 ms  iptfarmsa-scd-sw0-vla703.net.aol.com [207.200.12
0.30]
  3   437 ms   437 ms   437 ms  10.12.29.113
  4   437 ms   437 ms   437 ms  10.12.29.117
  5   437 ms   437 ms   437 ms  acl1-scd-ae0.atdn.net [10.12.17.2]
  6   437 ms   437 ms   437 ms  10.52.2.29
  7   437 ms   437 ms   437 ms  core1-scd-ae2.atdn.net [10.12.17.1]
  8   437 ms   437 ms   437 ms  dar1-scd-ae-0.atdn.net [66.185.152.33]
  9   437 ms   437 ms   437 ms  pop1-sjg-xe-2-1-0.atdn.net [66.185.152.26]
 10   453 ms   452 ms   452 ms  aws-pop1-sjg.atdn.net [66.185.150.130]
 11     *        *        *     Request timed out.
 12   468 ms   468 ms   468 ms  205.251.225.184
 13   468 ms   468 ms   468 ms  72.21.222.201
 14   468 ms   468 ms   453 ms  205.251.229.39
 15   484 ms   484 ms   484 ms  205.251.229.40
 16   484 ms   484 ms   483 ms  205.251.230.120
 17     *        *        *     Request timed out.
 18     *        *        *     Request timed out.
 19     *        *        *     Request timed out.
 20     *        *So, do you believe you learned something relevant to your issue by using the tracert command?  If so, what?

Browsing the web is going to frustrating will dialup; that's simply a fact.   The site you mentioned has some heavily-coded pages that are simply not going to load quickly, if at all, using dialup. Is a dialup Internet connection necessary for you for some reason?  Is a faster service not available in your area?