A tough choice, I have reinstalled windows several hundred maybe even thousand times now so.
Advantages: quicker (probably by about 10 minutes), some install discs like to wipe your drive beforehand and repair will not.
Disadvantages: You will have a program files folder full of junk you most likely will have to reinstall (unless you find all the registry stuff they use at which point you might as well not have bothered), same applies to an extent to Documents and Settings, your drive will probably still be fragmented.
My suggestion is grab a copy of nlite (
http://www.nliteos.com/ ) and make a nice custom install with all the drivers and tweaks you want (make sure you only kill stuff you know you do not need). Grab all the tools you might like. Here is my list, it is a bit old versions wise, misses a few choice apps I use these days and lacks links but it could help (everything save spinrite is free):
7z442.exe 7zip, a compression program (zip, rar etc)
94.24_forceware_winxp_international_whql.exe (nvidia drivers)
a2FreeSetup.exe (a squared free, a spyware type tool)
audacity-win-unicode-1.3.3-Vista.zip (an audio editor a la nero wave editor)
autoit-v3.2.2.0-setup.exe (auto it: a programming language)
avg75free (AVG anti virus: free)
avidemux_2.4_preview2_win32.zip (a video making program)
Avisynth_257.exe (a video editing program, very powerful)
AvsP_v1.4.0.zip (a text editor)
BonkEnc-1.0.4.zip (an audio encoder)
burrrn_package.exe (an audio CD maker)
CCCP-Insurgent-2006-01-01.exe (helps sort problems with codecs)
CFP_Setup_English_2.4.18.184.exe (comodo: firewall program)
Combined-Community-Codec-Pack-2007-07-22.exe (one of the best codec packs around, newer version)
CryptLoad7.5 (a program to automate rapidshare downloading)
dgavcdec100a5.zip (helps with HD/BD DVD)
DVDAuthorGUI_1.013.exe (helps make DVD menus and for burning)
dvdbasics (stuff to rip DVDs)
eac-0.95b4.zip (stuff to rip CDs)
eclipse.EXE (allows you to have a switch to turn you screen off, may be identified as a virus but it is not)
electronics (some basic electronics stuff)
FAVC_101.zip (makes DVDs from AVI/mpg/mkv...... files, needs AVIsynth)
Firefox Setup 2.0.0.4.exe (firefox, get a plugin called adblock+, filterset g and noscript)
FixVTS1.602.zip (helps fix broken DVDs that are not spec compliant)
foxitreader_setup.exe (a very good PDF reader)
FreePrimo32Setup.exe (helps "print" to a PDF file)
gaim-1.5.0.exe (chat program, trillian is also good)
gimp-2.2.15-i586-setup-1.exe (photoshop grade image editing)
GrabIt171b.exe (usenet downloader)
gtk+-2.10.11-setup.exe (needed for gimp and gaim as well as a few other apps)
gtk+-2.10.6-1-setup.zip (as above)
ImagoMPEG-Muxer.zip (for DVDs it helps a bit)
ImgBurn-2.3.2.0.zip (used to burn to CD/DVD, possibly the best around)
info.txt (this file)
moonshell171_with_dpgtools13.zip (helps make videos for the DS)
muxman_0_15R.zip (much like DVDAuthor GUI)
ofview.zip (open files viewer: tells what you have open on your system)
OOo_2.2.0_Win32Intel_install_wJRE_en-US.exe (free office software: smaller (perhaps 200Mbytes) and a fine replacement for MS Office)
QuEnc072.exe (encodes all sorts of video inlcuding PSP)
quicktimealt181lite.exe (alternative to quick time: if you want quick time use it)
realalt152lite.exe (alternative to real player: if you want real video/audio use it)
RegToy.7z (windows tweaker)
Ripit4me (helps rip new DVDs that are corrupted as a form of protection, also automates the process to an extent)
RipIt4Me.zip
Sequoia1.3Install.zip (displays the contents of your drive as a mesh of squares, good for hunting big files you forgot you had)
Sequoia1_3XPInstall.exe
shexview.zip (shell extension viewer: use to tweak stuff you do not need, quite advanced but go it anyway)
SoundOut-1.0.0.zip (plugin for avisynth, allows you to encode audio directly from avisynth)
SpinRite.iso (helps fix corrupt drives)
Spinrite_v6.00_Release1_Retail_Final.zip
spybotsd14.exe (spybot, used to detect spyware and the like)
TweakUiPowertoySetup.exe (windows tweaker)
tweakxputility.exe
vsfilter_20051125.7z
Wavosaur.1.0.0.7000.zip
wireshark-setup-0.99.5.exe
xp-AntiSpy_en.exe
YencPowerPostA&A11b.zip
