Ok at first I though: "slow startup, probably taking minutes to load" but your problem is far worse than that. Here's what I would do, in order I would do it:
1- Pyree told you to type msconfig, then in startup tab, you disable obsolete and unnecessary programs, like:
google update, any java you see (jusched is a java updater and is not needed at bootup), any updater you see (I don't like my computer being busy when I can do the updates myself at a better time), steam, msn, iTunes, hamachi, quicktime.
2- You can desactivate windows services that you don't need. To do so:
Control panel -> System & Security -> Administration tools -> Services.
Be aware that this can screw your windows if you don't know what your are desactivating. Go slowly, read the info given on each service you wanna stop, and you can even do some research on the internet for even more information on each services since it's not always clear. You can safetly desactivate these services if you don't need them right now (bear in mind that I'm using a french windows 7 so I translated the service names in english so the service names might differ a bit from my translation, sorry for that but hey, at least I'm helping you ^^):
- Adaptative brightness (usefull for laptops only)
- Automatic WWAN configuration (this one don't desactivate, only put on manual startup)
- Biometric Service (used only if you have a biometric sensor on your laptop)
- BitLocker Drive Encryption (Better to use TrueCrypt, which CAN work on ubuntu too, it's not the case of BitLocker)
- Bluetooth Support
- Bonjour Service (this one don't desactivate, only put on manual startup)
- Error Reporting Service (this one don't desactivate, only put on manual startup)
- Google Update Service
- iPod Service (this one don't desactivate, only put on manual startup)
- LogMeIn Hamachi 2.0 Tunelling Engine (I use this software for gameplay with my family over the internet, but not needed when not playing)
- NVIDIA Stereoscopic Driver Service (used for 3D, installed for everyone, but 5% of people are actually using it since you have to have a powerful graphic card, a 3D monitor, the glasses that go with the monitor and a game that supports 3D...)
- Smart card
- Parental Controls
- Remote Desktop
- Remote Registry
- Routing and Remote Access
- Service Media Center Extender
- Steam (you can load it manually when you wanna play, don't need it at bootup)
- Tablet PC Input
- Windows Backup (I don't like that service at all)
- Windows CardSpace (this one don't desactivate, only put on manual startup)
- Windows Connect Now
- Windows Defender (scrap from microsoft, does crash sometimes so better desactivate it)
- Windows Media Center Services (if you're not using your desktop as a HTPC, since most people don't, there is 2 services about windows media center, desactivate both)
- Windows Search (if you never search for files in your computer, furthermore it keeps the computer busy ALL THE TIME, I HATE IT!!!!!!)
- Windows Update (you can look for updates yourself)
After that a little reboot would be fine
3- Elsewhere you can desactivate a lot more things included right away in Windows 7. But for this you will have to be careful be going slowly and reading everything you come to before desactivating anything you don't know:
Go to Control panel -> System & Security -> Administration tools -> Task scheduler. In this thing you can configure anything that's making your computer busy at anytime, and even see when the next tasks will be executed (I like this thing I tell you ^^)
You can desactivate almost everything here since it's about 95% junk that makes your computer busy... First you have to open directories on the left side of your screen until you open Windows, then a lot of folders will then show. Click one, read on the right what's it about, then if you don't want one of the functions into a particular folder, just select it, then on the right portion of the screen there is an option to desactivate. Don't need to mess with the schedules since if you want it back it's easier to just activate it than reinputting schedules...
Again in that windows, desactivate any update you see, any "windows experience" you see. There is a lot more unnecessary junk to desactivate your gonna see. btw I desactivated almost anything, so that the only things that are now scheduled is: RacTask and RegIdleBackup. Everything else is junk for my tastes and needs.
4- Install CCleaner and do a full cleanup of your system (don't cleanup the registry as it COULD remove important things in your Windows. Better be safe than sorry.)
If you still wanna clear the registry, UNCHECK these boxes before doing so:
- ActiveX and invalid classes
- Unused file extensions
- Installator (it finds a lot of files that don't really are executables so better leave it off)
- Windows Services
5- Install "Spybot - Search & Destroy", do the updates, vaccine your computer, then do a scan with it, removing everything it finds. Your problem looks like spyware related so this is probably the cure to your problem.
6- Do an antivirus update then scan your whole system. Remove everything it finds.
If the problem still persists try the next step (coming right from my past experiences):
7- Disconnect your network cable, reboot your computer. If it is a lot faster then your problem is really virus/trojan/spyware related. You will have to correct this before anything is back to normal.
8- After doing everything else I would remove a lot of programs/games I'm not using anymore just to make sure there isn't any compatiblity issues preventing you from having a satisfactory experience with your computer.
9- The last step... reinstall Windows, that always works, but is a pain in the *** to reinstall everything your using.
I sincerely hope that will solve your problem without reinstalling. BTW my Windows 7 64bits is a few months old and it is already taking like 5 minutes to bootup everything and I tell you I removed everything not nessecary at bootup... Of course I installed a lot a programs and games so that might have crowed the windows registry a bit...