Begin by doing the typical computer maintenance tasks, i.e., run Disk
Cleanup, empty any remaining temp folders, Internet cache, etc.  Run
Scandisk and Defrag, in Safe Mode, if necessary.  Boot very cleanly, ending
any non-OS processes, using a process viewer to confirm.  Run the AV and
antispyware tools to confirm cleanliness.

Then examine the amount of free space on C:, where hopefully it will be 500
MB, or  more.

Connect to WU, and DL and install each Critical Update, one at a time.
Begin with any IE updates to improve the connection.
Only after all the Critical Updates, and any desired additional MS updates
are successfully installed, should you begin upgrading or installing any
third-party programs, such as the previously mentioned flash player.

I also recommend adding at least 128 MB of additional ram, if possible
technically and financially.
Most memory is very inexpensive now, and especially during this holiday
season, with numerous promo pricings.
Adding a 256 MB module, for a total of 384 MB of ram, would be very
beneficial.

If the amount of free space is too low, consider adding a new, larger,
faster HD, and making it the primary drive.
These are very inexpensive now, too.