well it depends.

*Do you feel that the speakers are decent right now?
If yes, then get the head unit. If, no replace speakers. Keep in mind if you buy a head unit from a chain store (like good guys or circuit city) its possible to get a really good deal. Sometimes you can get a headunit and free installation and theyll throw in free speakers. these speakers won't be outstanding but will be better than the stock ones. if you look you might be able to get both done (knock 2 birds down w/one stone). Do understand tho, if u do decide to keep the stock speakers that they will blow very easily at high volumes with your new head unit if u listen to your music loud.

However, if you are planning to redo your whole sound system (speakers and headunit) in the future, but don't have the funds yet id go for the speakers b/c the technology of speakers doesn't change as much as headunits do. ie. if you bought good speakers today they still will be good in a year or even 2. but if you bought a good head unit, it may be good in a year or two, but it will definitely be lacking some of the advanced features on the market.

again it comes down to personal preference and the deal you can get. Personally, i would get a headunit because i think the stock speakers are decent. In fact another approach i can suggest is getting a new head unit and a decent subwoofer then using the stock speakers as tweeters and midrange speakers basically. Ive heard this type of set up in my friends truck and it sounded surprisingly clean and good. many people here have taken that route too. but then again maybe a sub isn't what you want.
sorry for the long post, hope i helped or at least conveyed my opinion.

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1998 Ford Contour SVT
*Silver Frost/Midnight Blue
*New cupholders, ceg sticker =)
*BONE STOCK*


1998 E0 Ford Contour SVT
Built on 8/19/97 -- #3101/6535
Silver Frost/Midnight Blue
* New Cupholders * CEG sticker =) * 9005 Philips BlueVisions * Sound System: Kenwood eXcelon KDC-X617 HU, RFosgate fnq514 components, RFosgate 6x9 3ways, RFosgate 12" sub, MTX 5ch/800w amp, 1 Farad Cap * Removed Ford emblems * Fogs w/parking lights and aimed up * Brushed Aluminum Style Grills all around * 205/55/ZR16 Bridgestone Potenza RE730's * Removed Headliner * Visit MY SVT website (UNDER CONSTRUCTION)*