Originally Posted by Astor
Ctrl Alt Del, I'd echo Thanatos9t's sentiment that Oxford has some great sights, particularly Blenheim Palace.
It's a bit of a way outside Oxford, Astor.
It's also hideously expensive.
That's if you don't get distracted with the tons of stuff that there is to see in London - the Imperial War Museum in particular is brilliant, as is the Natural History Museum.
This is true.
General hint for planning purposes around London: The Houses of Parliament, Big Ben, Westminster Abbey and Westminster Cathedral are all right on top of one another (only one has free entry, though). The London Eye is, IIRC, on the other side of the river from Parliament, but if you walk over Westminster bridge, the South Bank is well worth taking a walk along if the weather's good, it'll give you a good view of the various big buildings around Embankment, and will also take you up to the Southbank Centre and the National Theatre. Then if you walk up and across Blackfriar's Bridge, you're in striking distance of St Paul's, and the Old Bailey.
Other places of interest: The Bank of England on Threadneedle Street is well worth a look, at least at the (vast) exterior, and is right next to St Mary Woolnoth, which is one of the little architectural gems hidden in the City.
The Victoria and Albert Museum (V&A) is also well worth a look.
Trafalgar Square is essential, and has the National Gallery and National Portrait Gallery one one side, but is also very close to Buckingham Palace, Horseguards Parade, Pall Mall and all that. It's also in the middle of the embassy zone, so be careful who you punch.
The British Museum is on Great Russell Street, which you can reach (if you really want to) by walking up Tottenham Court Road and walking through a side street. It's also about 15 minutes walk from Covent Garden, and according to Google maps, 40 minutes away from the Imperial War Museum, walking past the National Theatre (see above) and the Old Vic.
If you like architectural variety, visit Fleet Street, former home of almost all British newspapers (the Times included). The Express building in particular is worth looking out for. If you do go to Fleet Street don't miss visiting Ye Olde Cheshire Cheese pub at no. 145a. Supposedly it was rebuilt after the Great Fire in 1666, and was also meant to have been patronised by Oliver Goldsmith, Dr Johnson, Alfred Lord Tennyson, Sir Arthur Conan-Doyle, GK Chesterton, and some bloke called Mark Twain. The pub is down a little alley, so you may have difficulty finding it.
You might also want to visit one of the big parks in the city - Hyde Park (take note of the various speakers at its Corner), or Green Park come to mind.
In terms of getting around London, the bus system works but can be confusing and not all buses will let you buy tickets when you get on. The Underground (or "tube" to denizens of the city), however, has clear maps, and is very often late and horribly crowded, but is an essential part of the London experience. Be careful when taking it, however, as the distance between stations on the Tube Map bears no relation whatsoever to their geographical location - Bank and Monument are in fact IIRC the same station separated by a long corridor underground, and a couple of minutes' walk overground. Buying a tube map is a sensible precaution, nevertheless, and an Oyster Card will make it easier to get around.
You can get to Oxford probably most easily by train from Paddington. Reaching Paddington may be a problem if there's a tube strike, though, and I think there are buses. Once there, there a tourist buses, tours round the various colleges, general tours round the city, there's the Ashmolean Museum, the Pitt Rivers Museum, and so on, but other people can probably fill you in on it rather more.